MySQL :: MySQL 5.7 Reference Manual :: 13.7 Date and Time Functions

MySQL 5.7 Reference Manual / Functions and Operators / Date and Time Functions

13.7 Date and Time Functions

This section describes the functions that can be used to manipulate temporal values. See Section 12.3, “Date and Time Types”, for a description of the range of values each date and time type has and the valid formats in which values may be specified.

Table 13.13 Date/Time Functions

Name	Description
`ADDDATE()`	Add time values (intervals) to a date value
`ADDTIME()`	Add time
`CONVERT_TZ()`	Convert from one timezone to another
`CURDATE()`	Return the current date
`CURRENT_DATE()`, `CURRENT_DATE`	Synonyms for CURDATE()
`CURRENT_TIME()`, `CURRENT_TIME`	Synonyms for CURTIME()
`CURRENT_TIMESTAMP()`, `CURRENT_TIMESTAMP`	Synonyms for NOW()
`CURTIME()`	Return the current time
`DATE()`	Extract the date part of a date or datetime expression
`DATE_ADD()`	Add time values (intervals) to a date value
`DATE_FORMAT()`	Format date as specified
`DATE_SUB()`	Subtract a time value (interval) from a date
`DATEDIFF()`	Subtract two dates
`DAY()`	Synonym for DAYOFMONTH()
`DAYNAME()`	Return the name of the weekday
`DAYOFMONTH()`	Return the day of the month (0-31)
`DAYOFWEEK()`	Return the weekday index of the argument
`DAYOFYEAR()`	Return the day of the year (1-366)
`EXTRACT()`	Extract part of a date
`FROM_DAYS()`	Convert a day number to a date
`FROM_UNIXTIME()`	Format UNIX timestamp as a date
`GET_FORMAT()`	Return a date format string
`HOUR()`	Extract the hour
`LAST_DAY`	Return the last day of the month for the argument
`LOCALTIME()`, `LOCALTIME`	Synonym for NOW()
`LOCALTIMESTAMP`, `LOCALTIMESTAMP()`	Synonym for NOW()
`MAKEDATE()`	Create a date from the year and day of year
`MAKETIME()`	Create time from hour, minute, second
`MICROSECOND()`	Return the microseconds from argument
`MINUTE()`	Return the minute from the argument
`MONTH()`	Return the month from the date passed
`MONTHNAME()`	Return the name of the month
`NOW()`	Return the current date and time
`PERIOD_ADD()`	Add a period to a year-month
`PERIOD_DIFF()`	Return the number of months between periods
`QUARTER()`	Return the quarter from a date argument
`SEC_TO_TIME()`	Converts seconds to 'HH:MM:SS' format
`SECOND()`	Return the second (0-59)
`STR_TO_DATE()`	Convert a string to a date
`SUBDATE()`	Synonym for DATE_SUB() when invoked with three arguments
`SUBTIME()`	Subtract times
`SYSDATE()`	Return the time at which the function executes
`TIME()`	Extract the time portion of the expression passed
`TIME_FORMAT()`	Format as time
`TIME_TO_SEC()`	Return the argument converted to seconds
`TIMEDIFF()`	Subtract time
`TIMESTAMP()`	With a single argument, this function returns the date or datetime expression; with two arguments, the sum of the arguments
`TIMESTAMPADD()`	Add an interval to a datetime expression
`TIMESTAMPDIFF()`	Subtract an interval from a datetime expression
`TO_DAYS()`	Return the date argument converted to days
`TO_SECONDS()`	Return the date or datetime argument converted to seconds since Year 0
`UNIX_TIMESTAMP()`	Return a UNIX timestamp
`UTC_DATE()`	Return the current UTC date
`UTC_TIME()`	Return the current UTC time
`UTC_TIMESTAMP()`	Return the current UTC date and time
`WEEK()`	Return the week number
`WEEKDAY()`	Return the weekday index
`WEEKOFYEAR()`	Return the calendar week of the date (1-53)
`YEAR()`	Return the year
`YEARWEEK()`	Return the year and week

Here is an example that uses date functions. The following query selects all rows with a date_col value from within the last 30 days:

mysql> SELECT something FROM tbl_name
    -> WHERE DATE_SUB(CURDATE(),INTERVAL 30 DAY) <= date_col;

The query also selects rows with dates that lie in the future.

Functions that expect date values usually accept datetime values and ignore the time part. Functions that expect time values usually accept datetime values and ignore the date part.

Functions that return the current date or time each are evaluated only once per query at the start of query execution. This means that multiple references to a function such as NOW() within a single query always produce the same result. (For our purposes, a single query also includes a call to a stored program (stored routine, trigger, or event) and all subprograms called by that program.) This principle also applies to CURDATE(), CURTIME(), UTC_DATE(), UTC_TIME(), UTC_TIMESTAMP(), and to any of their synonyms.

The CURRENT_TIMESTAMP(), CURRENT_TIME(), CURRENT_DATE(), and FROM_UNIXTIME() functions return values in the connection's current time zone, which is available as the value of the time_zone system variable. In addition, UNIX_TIMESTAMP() assumes that its argument is a datetime value in the current time zone. See Section 11.6, “MySQL Server Time Zone Support”.

Some date functions can be used with “zero” dates or incomplete dates such as '2001-11-00', whereas others cannot. Functions that extract parts of dates typically work with incomplete dates and thus can return 0 when you might otherwise expect a nonzero value. For example:

mysql> SELECT DAYOFMONTH('2001-11-00'), MONTH('2005-00-00');
        -> 0, 0

Other functions expect complete dates and return NULL for incomplete dates. These include functions that perform date arithmetic or that map parts of dates to names. For example:

mysql> SELECT DATE_ADD('2006-05-00',INTERVAL 1 DAY);
        -> NULL
mysql> SELECT DAYNAME('2006-05-00');
        -> NULL

Several functions are more strict when passed a DATE() function value as their argument and reject incomplete dates with a day part of zero. These functions are affected: CONVERT_TZ(), DATE_ADD(), DATE_SUB(), DAYOFYEAR(), LAST_DAY() (permits a day part of zero), TIMESTAMPDIFF(), TO_DAYS(), TO_SECONDS(), WEEK(), WEEKDAY(), WEEKOFYEAR(), YEARWEEK().

Fractional seconds for TIME, DATETIME, and TIMESTAMP values are supported, with up to microsecond precision. Functions that take temporal arguments accept values with fractional seconds. Return values from temporal functions include fractional seconds as appropriate.

ADDDATE(date,INTERVAL expr unit), ADDDATE(expr,days)
When invoked with the INTERVAL form of the second argument, ADDDATE() is a synonym for DATE_ADD(). The related function SUBDATE() is a synonym for DATE_SUB(). For information on the INTERVAL unit argument, see the discussion for DATE_ADD().
```
mysql> SELECT DATE_ADD('2008-01-02', INTERVAL 31 DAY);
        -> '2008-02-02'
mysql> SELECT ADDDATE('2008-01-02', INTERVAL 31 DAY);
        -> '2008-02-02'
```
When invoked with the days form of the second argument, MySQL treats it as an integer number of days to be added to expr.
```
mysql> SELECT ADDDATE('2008-01-02', 31);
        -> '2008-02-02'
```

ADDTIME(expr1,expr2)

ADDTIME() adds expr2 to expr1 and returns the result. expr1 is a time or datetime expression, and expr2 is a time expression.

mysql> SELECT ADDTIME('2007-12-31 23:59:59.999999', '1 1:1:1.000002');
        -> '2008-01-02 01:01:01.000001'
mysql> SELECT ADDTIME('01:00:00.999999', '02:00:00.999998');
        -> '03:00:01.999997'

CONVERT_TZ(dt,from_tz,to_tz)
CONVERT_TZ() converts a datetime value dt from the time zone given by from_tz to the time zone given by to_tz and returns the resulting value. Time zones are specified as described in Section 11.6, “MySQL Server Time Zone Support”. This function returns NULL if the arguments are invalid.
If the value falls out of the supported range of the TIMESTAMP type when converted from from_tz to UTC, no conversion occurs. The TIMESTAMP range is described in Section 12.1.2, “Date and Time Type Overview”.
```
mysql> SELECT CONVERT_TZ('2004-01-01 12:00:00','GMT','MET');
        -> '2004-01-01 13:00:00'
mysql> SELECT CONVERT_TZ('2004-01-01 12:00:00','+00:00','+10:00');
        -> '2004-01-01 22:00:00'
```
Note

To use named time zones such as 'MET' or 'Europe/Moscow', the time zone tables must be properly set up. See Section 11.6, “MySQL Server Time Zone Support”, for instructions.
CURDATE()
Returns the current date as a value in 'YYYY-MM-DD' or YYYYMMDD format, depending on whether the function is used in a string or numeric context.
```
mysql> SELECT CURDATE();
        -> '2008-06-13'
mysql> SELECT CURDATE() + 0;
        -> 20080613
```
CURRENT_DATE, CURRENT_DATE()
CURRENT_DATE and CURRENT_DATE() are synonyms for CURDATE().
CURRENT_TIME, CURRENT_TIME([fsp])
CURRENT_TIME and CURRENT_TIME() are synonyms for CURTIME().
CURRENT_TIMESTAMP, CURRENT_TIMESTAMP([fsp])
CURRENT_TIMESTAMP and CURRENT_TIMESTAMP() are synonyms for NOW().
CURTIME([fsp])
Returns the current time as a value in 'HH:MM:SS' or HHMMSS format, depending on whether the function is used in a string or numeric context. The value is expressed in the current time zone.
If the fsp argument is given to specify a fractional seconds precision from 0 to 6, the return value includes a fractional seconds part of that many digits.
```
mysql> SELECT CURTIME();
        -> '23:50:26'
mysql> SELECT CURTIME() + 0;
        -> 235026.000000
```

DATE(expr)

Extracts the date part of the date or datetime expression expr.

mysql> SELECT DATE('2003-12-31 01:02:03');
        -> '2003-12-31'

DATEDIFF(expr1,expr2)
DATEDIFF() returns expr1 − expr2 expressed as a value in days from one date to the other. expr1 and expr2 are date or date-and-time expressions. Only the date parts of the values are used in the calculation.
```
mysql> SELECT DATEDIFF('2007-12-31 23:59:59','2007-12-30');
        -> 1
mysql> SELECT DATEDIFF('2010-11-30 23:59:59','2010-12-31');
        -> -31
```

DATE_ADD(date,INTERVAL expr unit), DATE_SUB(date,INTERVAL expr unit)

These functions perform date arithmetic. The date argument specifies the starting date or datetime value. expr is an expression specifying the interval value to be added or subtracted from the starting date. expr is a string; it may start with a “-” for negative intervals. unit is a keyword indicating the units in which the expression should be interpreted.

The INTERVAL keyword and the unit specifier are not case sensitive.

The following table shows the expected form of the expr argument for each unit value.

`unit` Value	Expected `expr` Format
`MICROSECOND`	`MICROSECONDS`
`SECOND`	`SECONDS`
`MINUTE`	`MINUTES`
`HOUR`	`HOURS`
`DAY`	`DAYS`
`WEEK`	`WEEKS`
`MONTH`	`MONTHS`
`QUARTER`	`QUARTERS`
`YEAR`	`YEARS`
`SECOND_MICROSECOND`	`'SECONDS.MICROSECONDS'`
`MINUTE_MICROSECOND`	`'MINUTES:SECONDS.MICROSECONDS'`
`MINUTE_SECOND`	`'MINUTES:SECONDS'`
`HOUR_MICROSECOND`	`'HOURS:MINUTES:SECONDS.MICROSECONDS'`
`HOUR_SECOND`	`'HOURS:MINUTES:SECONDS'`
`HOUR_MINUTE`	`'HOURS:MINUTES'`
`DAY_MICROSECOND`	`'DAYS HOURS:MINUTES:SECONDS.MICROSECONDS'`
`DAY_SECOND`	`'DAYS HOURS:MINUTES:SECONDS'`
`DAY_MINUTE`	`'DAYS HOURS:MINUTES'`
`DAY_HOUR`	`'DAYS HOURS'`
`YEAR_MONTH`	`'YEARS-MONTHS'`

The return value depends on the arguments:

DATETIME if the first argument is a DATETIME (or TIMESTAMP) value, or if the first argument is a DATE and the unit value uses HOURS, MINUTES, or SECONDS.
String otherwise.

To ensure that the result is DATETIME, you can use CAST() to convert the first argument to DATETIME.

MySQL permits any punctuation delimiter in the expr format. Those shown in the table are the suggested delimiters. If the date argument is a DATE value and your calculations involve only YEAR, MONTH, and DAY parts (that is, no time parts), the result is a DATE value. Otherwise, the result is a DATETIME value.

Date arithmetic also can be performed using INTERVAL together with the + or - operator:

date + INTERVAL expr unit
date - INTERVAL expr unit

INTERVAL expr unit is permitted on either side of the + operator if the expression on the other side is a date or datetime value. For the - operator, INTERVAL expr unit is permitted only on the right side, because it makes no sense to subtract a date or datetime value from an interval.

mysql> SELECT '2008-12-31 23:59:59' + INTERVAL 1 SECOND;
        -> '2009-01-01 00:00:00'
mysql> SELECT INTERVAL 1 DAY + '2008-12-31';
        -> '2009-01-01'
mysql> SELECT '2005-01-01' - INTERVAL 1 SECOND;
        -> '2004-12-31 23:59:59'
mysql> SELECT DATE_ADD('2000-12-31 23:59:59',
    ->                 INTERVAL 1 SECOND);
        -> '2001-01-01 00:00:00'
mysql> SELECT DATE_ADD('2010-12-31 23:59:59',
    ->                 INTERVAL 1 DAY);
        -> '2011-01-01 23:59:59'
mysql> SELECT DATE_ADD('2100-12-31 23:59:59',
    ->                 INTERVAL '1:1' MINUTE_SECOND);
        -> '2101-01-01 00:01:00'
mysql> SELECT DATE_SUB('2005-01-01 00:00:00',
    ->                 INTERVAL '1 1:1:1' DAY_SECOND);
        -> '2004-12-30 22:58:59'
mysql> SELECT DATE_ADD('1900-01-01 00:00:00',
    ->                 INTERVAL '-1 10' DAY_HOUR);
        -> '1899-12-30 14:00:00'
mysql> SELECT DATE_SUB('1998-01-02', INTERVAL 31 DAY);
        -> '1997-12-02'
mysql> SELECT DATE_ADD('1992-12-31 23:59:59.000002',
    ->            INTERVAL '1.999999' SECOND_MICROSECOND);
        -> '1993-01-01 00:00:01.000001'

If you specify an interval value that is too short (does not include all the interval parts that would be expected from the unit keyword), MySQL assumes that you have left out the leftmost parts of the interval value. For example, if you specify a unit of DAY_SECOND, the value of expr is expected to have days, hours, minutes, and seconds parts. If you specify a value like '1:10', MySQL assumes that the days and hours parts are missing and the value represents minutes and seconds. In other words, '1:10' DAY_SECOND is interpreted in such a way that it is equivalent to '1:10' MINUTE_SECOND. This is analogous to the way that MySQL interprets TIME values as representing elapsed time rather than as a time of day.

Because expr is treated as a string, be careful if you specify a nonstring value with INTERVAL. For example, with an interval specifier of HOUR_MINUTE, 6/4 evaluates to 1.5000 and is treated as 1 hour, 5000 minutes:

mysql> SELECT 6/4;
        -> 1.5000
mysql> SELECT DATE_ADD('2009-01-01', INTERVAL 6/4 HOUR_MINUTE);
        -> '2009-01-04 12:20:00'

To ensure interpretation of the interval value as you expect, a CAST() operation may be used. To treat 6/4 as 1 hour, 5 minutes, cast it to a DECIMAL value with a single fractional digit:

mysql> SELECT CAST(6/4 AS DECIMAL(3,1));
        -> 1.5
mysql> SELECT DATE_ADD('1970-01-01 12:00:00',
    ->                 INTERVAL CAST(6/4 AS DECIMAL(3,1)) HOUR_MINUTE);
        -> '1970-01-01 13:05:00'

If you add to or subtract from a date value something that contains a time part, the result is automatically converted to a datetime value:

mysql> SELECT DATE_ADD('2013-01-01', INTERVAL 1 DAY);
        -> '2013-01-02'
mysql> SELECT DATE_ADD('2013-01-01', INTERVAL 1 HOUR);
        -> '2013-01-01 01:00:00'

If you add MONTH, YEAR_MONTH, or YEAR and the resulting date has a day that is larger than the maximum day for the new month, the day is adjusted to the maximum days in the new month:

mysql> SELECT DATE_ADD('2009-01-30', INTERVAL 1 MONTH);
        -> '2009-02-28'

Date arithmetic operations require complete dates and do not work with incomplete dates such as '2006-07-00' or badly malformed dates:

mysql> SELECT DATE_ADD('2006-07-00', INTERVAL 1 DAY);
        -> NULL
mysql> SELECT '2005-03-32' + INTERVAL 1 MONTH;
        -> NULL

DATE_FORMAT(date,format)

Formats the date value according to the format string.

The following specifiers may be used in the format string. The “%” character is required before format specifier characters.

Specifier	Description
`%a`	Abbreviated weekday name (`Sun`..`Sat`)
`%b`	Abbreviated month name (`Jan`..`Dec`)
`%c`	Month, numeric (`0`..`12`)
`%D`	Day of the month with English suffix (`0th`, `1st`, `2nd`, `3rd`, …)
`%d`	Day of the month, numeric (`00`..`31`)
`%e`	Day of the month, numeric (`0`..`31`)
`%f`	Microseconds (`000000`..`999999`)
`%H`	Hour (`00`..`23`)
`%h`	Hour (`01`..`12`)
`%I`	Hour (`01`..`12`)
`%i`	Minutes, numeric (`00`..`59`)
`%j`	Day of year (`001`..`366`)
`%k`	Hour (`0`..`23`)
`%l`	Hour (`1`..`12`)
`%M`	Month name (`January`..`December`)
`%m`	Month, numeric (`00`..`12`)
`%p`	`AM` or `PM`
`%r`	Time, 12-hour (`hh:mm:ss` followed by `AM` or `PM`)
`%S`	Seconds (`00`..`59`)
`%s`	Seconds (`00`..`59`)
`%T`	Time, 24-hour (`hh:mm:ss`)
`%U`	Week (`00`..`53`), where Sunday is the first day of the week; `WEEK()` mode 0
`%u`	Week (`00`..`53`), where Monday is the first day of the week; `WEEK()` mode 1
`%V`	Week (`01`..`53`), where Sunday is the first day of the week; `WEEK()` mode 2; used with `%X`
`%v`	Week (`01`..`53`), where Monday is the first day of the week; `WEEK()` mode 3; used with `%x`
`%W`	Weekday name (`Sunday`..`Saturday`)
`%w`	Day of the week (`0`=Sunday..`6`=Saturday)
`%X`	Year for the week where Sunday is the first day of the week, numeric, four digits; used with `%V`
`%x`	Year for the week, where Monday is the first day of the week, numeric, four digits; used with `%v`
`%Y`	Year, numeric, four digits
`%y`	Year, numeric (two digits)
`%%`	A literal “`%`” character
`%x`	`x`, for any “`x`” not listed above

Ranges for the month and day specifiers begin with zero due to the fact that MySQL permits the storing of incomplete dates such as '2014-00-00'.

The language used for day and month names and abbreviations is controlled by the value of the lc_time_names system variable (Section 11.7, “MySQL Server Locale Support”).

For the %U, %u, %V, and %v specifiers, see the description of the WEEK() function for information about the mode values. The mode affects how week numbering occurs.

DATE_FORMAT() returns a string with a character set and collation given by character_set_connection and collation_connection so that it can return month and weekday names containing non-ASCII characters.

mysql> SELECT DATE_FORMAT('2009-10-04 22:23:00', '%W %M %Y');
        -> 'Sunday October 2009'
mysql> SELECT DATE_FORMAT('2007-10-04 22:23:00', '%H:%i:%s');
        -> '22:23:00'
mysql> SELECT DATE_FORMAT('1900-10-04 22:23:00',
    ->                 '%D %y %a %d %m %b %j');
        -> '4th 00 Thu 04 10 Oct 277'
mysql> SELECT DATE_FORMAT('1997-10-04 22:23:00',
    ->                 '%H %k %I %r %T %S %w');
        -> '22 22 10 10:23:00 PM 22:23:00 00 6'
mysql> SELECT DATE_FORMAT('1999-01-01', '%X %V');
        -> '1998 52'
mysql> SELECT DATE_FORMAT('2006-06-00', '%d');
        -> '00'

DATE_SUB(date,INTERVAL expr unit)
See the description for DATE_ADD().
DAY(date)
DAY() is a synonym for DAYOFMONTH().
DAYNAME(date)
Returns the name of the weekday for date. The language used for the name is controlled by the value of the lc_time_names system variable (Section 11.7, “MySQL Server Locale Support”).
```
mysql> SELECT DAYNAME('2007-02-03');
        -> 'Saturday'
```
DAYOFMONTH(date)
Returns the day of the month for date, in the range 1 to 31, or 0 for dates such as '0000-00-00' or '2008-00-00' that have a zero day part.
```
mysql> SELECT DAYOFMONTH('2007-02-03');
        -> 3
```
DAYOFWEEK(date)
Returns the weekday index for date (1 = Sunday, 2 = Monday, …, 7 = Saturday). These index values correspond to the ODBC standard.
```
mysql> SELECT DAYOFWEEK('2007-02-03');
        -> 7
```
DAYOFYEAR(date)
Returns the day of the year for date, in the range 1 to 366.
```
mysql> SELECT DAYOFYEAR('2007-02-03');
        -> 34
```

EXTRACT(unit FROM date)

The EXTRACT() function uses the same kinds of unit specifiers as DATE_ADD() or DATE_SUB(), but extracts parts from the date rather than performing date arithmetic.

mysql> SELECT EXTRACT(YEAR FROM '2009-07-02');
       -> 2009
mysql> SELECT EXTRACT(YEAR_MONTH FROM '2009-07-02 01:02:03');
       -> 200907
mysql> SELECT EXTRACT(DAY_MINUTE FROM '2009-07-02 01:02:03');
       -> 20102
mysql> SELECT EXTRACT(MICROSECOND
    ->                FROM '2003-01-02 10:30:00.000123');
        -> 123

FROM_DAYS(N)
Given a day number N, returns a DATE value.
```
mysql> SELECT FROM_DAYS(730669);
        -> '2007-07-03'
```
Use FROM_DAYS() with caution on old dates. It is not intended for use with values that precede the advent of the Gregorian calendar (1582). See Section 13.8, “What Calendar Is Used By MySQL?”.
FROM_UNIXTIME(unix_timestamp), FROM_UNIXTIME(unix_timestamp,format)
Returns a representation of the unix_timestamp argument as a value in 'YYYY-MM-DD HH:MM:SS' or YYYYMMDDHHMMSS format, depending on whether the function is used in a string or numeric context. The value is expressed in the current time zone. unix_timestamp is an internal timestamp value such as is produced by the UNIX_TIMESTAMP() function.
If format is given, the result is formatted according to the format string, which is used the same way as listed in the entry for the DATE_FORMAT() function.
```
mysql> SELECT FROM_UNIXTIME(1447430881);
        -> '2015-11-13 10:08:01'
mysql> SELECT FROM_UNIXTIME(1447430881) + 0;
        -> 20151113100801
mysql> SELECT FROM_UNIXTIME(UNIX_TIMESTAMP(),
    ->                      '%Y %D %M %h:%i:%s %x');
        -> '2015 13th November 10:08:01 2015'
```
Note: If you use UNIX_TIMESTAMP() and FROM_UNIXTIME() to convert between TIMESTAMP values and Unix timestamp values, the conversion is lossy because the mapping is not one-to-one in both directions. For details, see the description of the UNIX_TIMESTAMP() function.

GET_FORMAT({DATE|TIME|DATETIME}, {'EUR'|'USA'|'JIS'|'ISO'|'INTERNAL'})

Returns a format string. This function is useful in combination with the DATE_FORMAT() and the STR_TO_DATE() functions.

The possible values for the first and second arguments result in several possible format strings (for the specifiers used, see the table in the DATE_FORMAT() function description). ISO format refers to ISO 9075, not ISO 8601.

Function Call	Result
`GET_FORMAT(DATE,'USA')`	`'%m.%d.%Y'`
`GET_FORMAT(DATE,'JIS')`	`'%Y-%m-%d'`
`GET_FORMAT(DATE,'ISO')`	`'%Y-%m-%d'`
`GET_FORMAT(DATE,'EUR')`	`'%d.%m.%Y'`
`GET_FORMAT(DATE,'INTERNAL')`	`'%Y%m%d'`
`GET_FORMAT(DATETIME,'USA')`	`'%Y-%m-%d %H.%i.%s'`
`GET_FORMAT(DATETIME,'JIS')`	`'%Y-%m-%d %H:%i:%s'`
`GET_FORMAT(DATETIME,'ISO')`	`'%Y-%m-%d %H:%i:%s'`
`GET_FORMAT(DATETIME,'EUR')`	`'%Y-%m-%d %H.%i.%s'`
`GET_FORMAT(DATETIME,'INTERNAL')`	`'%Y%m%d%H%i%s'`
`GET_FORMAT(TIME,'USA')`	`'%h:%i:%s %p'`
`GET_FORMAT(TIME,'JIS')`	`'%H:%i:%s'`
`GET_FORMAT(TIME,'ISO')`	`'%H:%i:%s'`
`GET_FORMAT(TIME,'EUR')`	`'%H.%i.%s'`
`GET_FORMAT(TIME,'INTERNAL')`	`'%H%i%s'`

TIMESTAMP can also be used as the first argument to GET_FORMAT(), in which case the function returns the same values as for DATETIME.

mysql> SELECT DATE_FORMAT('2003-10-03',GET_FORMAT(DATE,'EUR'));
        -> '03.10.2003'
mysql> SELECT STR_TO_DATE('10.31.2003',GET_FORMAT(DATE,'USA'));
        -> '2003-10-31'

HOUR(time)
Returns the hour for time. The range of the return value is 0 to 23 for time-of-day values. However, the range of TIME values actually is much larger, so HOUR can return values greater than 23.
```
mysql> SELECT HOUR('10:05:03');
        -> 10
mysql> SELECT HOUR('272:59:59');
        -> 272
```

LAST_DAY(date)

Takes a date or datetime value and returns the corresponding value for the last day of the month. Returns NULL if the argument is invalid.

mysql> SELECT LAST_DAY('2003-02-05');
        -> '2003-02-28'
mysql> SELECT LAST_DAY('2004-02-05');
        -> '2004-02-29'
mysql> SELECT LAST_DAY('2004-01-01 01:01:01');
        -> '2004-01-31'
mysql> SELECT LAST_DAY('2003-03-32');
        -> NULL

LOCALTIME, LOCALTIME([fsp])
LOCALTIME and LOCALTIME() are synonyms for NOW().
LOCALTIMESTAMP, LOCALTIMESTAMP([fsp])
LOCALTIMESTAMP and LOCALTIMESTAMP() are synonyms for NOW().

MAKEDATE(year,dayofyear)

Returns a date, given year and day-of-year values. dayofyear must be greater than 0 or the result is NULL.

mysql> SELECT MAKEDATE(2011,31), MAKEDATE(2011,32);
        -> '2011-01-31', '2011-02-01'
mysql> SELECT MAKEDATE(2011,365), MAKEDATE(2014,365);
        -> '2011-12-31', '2014-12-31'
mysql> SELECT MAKEDATE(2011,0);
        -> NULL

MAKETIME(hour,minute,second)
Returns a time value calculated from the hour, minute, and second arguments.
The second argument can have a fractional part.
```
mysql> SELECT MAKETIME(12,15,30);
        -> '12:15:30'
```

MICROSECOND(expr)

Returns the microseconds from the time or datetime expression expr as a number in the range from 0 to 999999.

mysql> SELECT MICROSECOND('12:00:00.123456');
        -> 123456
mysql> SELECT MICROSECOND('2009-12-31 23:59:59.000010');
        -> 10

MINUTE(time)

Returns the minute for time, in the range 0 to 59.

mysql> SELECT MINUTE('2008-02-03 10:05:03');
        -> 5

MONTH(date)
Returns the month for date, in the range 1 to 12 for January to December, or 0 for dates such as '0000-00-00' or '2008-00-00' that have a zero month part.
```
mysql> SELECT MONTH('2008-02-03');
        -> 2
```
MONTHNAME(date)
Returns the full name of the month for date. The language used for the name is controlled by the value of the lc_time_names system variable (Section 11.7, “MySQL Server Locale Support”).
```
mysql> SELECT MONTHNAME('2008-02-03');
        -> 'February'
```
NOW([fsp])
Returns the current date and time as a value in 'YYYY-MM-DD HH:MM:SS' or YYYYMMDDHHMMSS format, depending on whether the function is used in a string or numeric context. The value is expressed in the current time zone.
If the fsp argument is given to specify a fractional seconds precision from 0 to 6, the return value includes a fractional seconds part of that many digits.
```
mysql> SELECT NOW();
        -> '2007-12-15 23:50:26'
mysql> SELECT NOW() + 0;
        -> 20071215235026.000000
```
NOW() returns a constant time that indicates the time at which the statement began to execute. (Within a stored function or trigger, NOW() returns the time at which the function or triggering statement began to execute.) This differs from the behavior for SYSDATE(), which returns the exact time at which it executes.
```
mysql> SELECT NOW(), SLEEP(2), NOW();
+---------------------+----------+---------------------+
| NOW()               | SLEEP(2) | NOW()               |
+---------------------+----------+---------------------+
| 2006-04-12 13:47:36 |        0 | 2006-04-12 13:47:36 |
+---------------------+----------+---------------------+

mysql> SELECT SYSDATE(), SLEEP(2), SYSDATE();
+---------------------+----------+---------------------+
| SYSDATE()           | SLEEP(2) | SYSDATE()           |
+---------------------+----------+---------------------+
| 2006-04-12 13:47:44 |        0 | 2006-04-12 13:47:46 |
+---------------------+----------+---------------------+
```
In addition, the SET TIMESTAMP statement affects the value returned by NOW() but not by SYSDATE(). This means that timestamp settings in the binary log have no effect on invocations of SYSDATE(). Setting the timestamp to a nonzero value causes each subsequent invocation of NOW() to return that value. Setting the timestamp to zero cancels this effect so that NOW() once again returns the current date and time.
See the description for SYSDATE() for additional information about the differences between the two functions.
PERIOD_ADD(P,N)
Adds N months to period P (in the format YYMM or YYYYMM). Returns a value in the format YYYYMM. Note that the period argument P is not a date value.
```
mysql> SELECT PERIOD_ADD(200801,2);
        -> 200803
```
PERIOD_DIFF(P1,P2)
Returns the number of months between periods P1 and P2. P1 and P2 should be in the format YYMM or YYYYMM. Note that the period arguments P1 and P2 are not date values.
```
mysql> SELECT PERIOD_DIFF(200802,200703);
        -> 11
```
QUARTER(date)
Returns the quarter of the year for date, in the range 1 to 4.
```
mysql> SELECT QUARTER('2008-04-01');
        -> 2
```
SECOND(time)
Returns the second for time, in the range 0 to 59.
```
mysql> SELECT SECOND('10:05:03');
        -> 3
```
SEC_TO_TIME(seconds)
Returns the seconds argument, converted to hours, minutes, and seconds, as a TIME value. The range of the result is constrained to that of the TIME data type. A warning occurs if the argument corresponds to a value outside that range.
```
mysql> SELECT SEC_TO_TIME(2378);
        -> '00:39:38'
mysql> SELECT SEC_TO_TIME(2378) + 0;
        -> 3938
```
STR_TO_DATE(str,format)
This is the inverse of the DATE_FORMAT() function. It takes a string str and a format string format. STR_TO_DATE() returns a DATETIME value if the format string contains both date and time parts, or a DATE or TIME value if the string contains only date or time parts. If the date, time, or datetime value extracted from str is illegal, STR_TO_DATE() returns NULL and produces a warning.
The server scans str attempting to match format to it. The format string can contain literal characters and format specifiers beginning with %. Literal characters in format must match literally in str. Format specifiers in format must match a date or time part in str. For the specifiers that can be used in format, see the DATE_FORMAT() function description.
```
mysql> SELECT STR_TO_DATE('01,5,2013','%d,%m,%Y');
        -> '2013-05-01'
mysql> SELECT STR_TO_DATE('May 1, 2013','%M %d,%Y');
        -> '2013-05-01'
```
Scanning starts at the beginning of str and fails if format is found not to match. Extra characters at the end of str are ignored.
```
mysql> SELECT STR_TO_DATE('a09:30:17','a%h:%i:%s');
        -> '09:30:17'
mysql> SELECT STR_TO_DATE('a09:30:17','%h:%i:%s');
        -> NULL
mysql> SELECT STR_TO_DATE('09:30:17a','%h:%i:%s');
        -> '09:30:17'
```
Unspecified date or time parts have a value of 0, so incompletely specified values in str produce a result with some or all parts set to 0:
```
mysql> SELECT STR_TO_DATE('abc','abc');
        -> '0000-00-00'
mysql> SELECT STR_TO_DATE('9','%m');
        -> '0000-09-00'
mysql> SELECT STR_TO_DATE('9','%s');
        -> '00:00:09'
```
Range checking on the parts of date values is as described in Section 12.3.1, “The DATE, DATETIME, and TIMESTAMP Types”. This means, for example, that “zero” dates or dates with part values of 0 are permitted unless the SQL mode is set to disallow such values.
```
mysql> SELECT STR_TO_DATE('00/00/0000', '%m/%d/%Y');
        -> '0000-00-00'
mysql> SELECT STR_TO_DATE('04/31/2004', '%m/%d/%Y');
        -> '2004-04-31'
```
If the NO_ZERO_DATE or NO_ZERO_IN_DATE SQL mode is enabled, zero dates or part of dates are disallowed. In that case, STR_TO_DATE() returns NULL and generates a warning:
```
mysql> SET sql_mode = '';
mysql> SELECT STR_TO_DATE('15:35:00', '%H:%i:%s');
+-------------------------------------+
| STR_TO_DATE('15:35:00', '%H:%i:%s') |
+-------------------------------------+
| 15:35:00                            |
+-------------------------------------+
mysql> SET sql_mode = 'NO_ZERO_IN_DATE';
mysql> SELECT STR_TO_DATE('15:35:00', '%h:%i:%s');
+-------------------------------------+
| STR_TO_DATE('15:35:00', '%h:%i:%s') |
+-------------------------------------+
| NULL                                |
+-------------------------------------+
mysql> SHOW WARNINGS\G
*************************** 1. row ***************************
  Level: Warning
   Code: 1411
Message: Incorrect datetime value: '15:35:00' for function str_to_date
```
Note

You cannot use format "%X%V" to convert a year-week string to a date because the combination of a year and week does not uniquely identify a year and month if the week crosses a month boundary. To convert a year-week to a date, you should also specify the weekday:
```
mysql> SELECT STR_TO_DATE('200442 Monday', '%X%V %W');
        -> '2004-10-18'
```
SUBDATE(date,INTERVAL expr unit), SUBDATE(expr,days)
When invoked with the INTERVAL form of the second argument, SUBDATE() is a synonym for DATE_SUB(). For information on the INTERVAL unit argument, see the discussion for DATE_ADD().
```
mysql> SELECT DATE_SUB('2008-01-02', INTERVAL 31 DAY);
        -> '2007-12-02'
mysql> SELECT SUBDATE('2008-01-02', INTERVAL 31 DAY);
        -> '2007-12-02'
```
The second form enables the use of an integer value for days. In such cases, it is interpreted as the number of days to be subtracted from the date or datetime expression expr.
```
mysql> SELECT SUBDATE('2008-01-02 12:00:00', 31);
        -> '2007-12-02 12:00:00'
```

SUBTIME(expr1,expr2)

SUBTIME() returns expr1 − expr2 expressed as a value in the same format as expr1. expr1 is a time or datetime expression, and expr2 is a time expression.

mysql> SELECT SUBTIME('2007-12-31 23:59:59.999999','1 1:1:1.000002');
        -> '2007-12-30 22:58:58.999997'
mysql> SELECT SUBTIME('01:00:00.999999', '02:00:00.999998');
        -> '-00:59:59.999999'

SYSDATE([fsp])
Returns the current date and time as a value in 'YYYY-MM-DD HH:MM:SS' or YYYYMMDDHHMMSS format, depending on whether the function is used in a string or numeric context.
If the fsp argument is given to specify a fractional seconds precision from 0 to 6, the return value includes a fractional seconds part of that many digits. Before 5.6.4, any argument is ignored.
SYSDATE() returns the time at which it executes. This differs from the behavior for NOW(), which returns a constant time that indicates the time at which the statement began to execute. (Within a stored function or trigger, NOW() returns the time at which the function or triggering statement began to execute.)
```
mysql> SELECT NOW(), SLEEP(2), NOW();
+---------------------+----------+---------------------+
| NOW()               | SLEEP(2) | NOW()               |
+---------------------+----------+---------------------+
| 2006-04-12 13:47:36 |        0 | 2006-04-12 13:47:36 |
+---------------------+----------+---------------------+

mysql> SELECT SYSDATE(), SLEEP(2), SYSDATE();
+---------------------+----------+---------------------+
| SYSDATE()           | SLEEP(2) | SYSDATE()           |
+---------------------+----------+---------------------+
| 2006-04-12 13:47:44 |        0 | 2006-04-12 13:47:46 |
+---------------------+----------+---------------------+
```
In addition, the SET TIMESTAMP statement affects the value returned by NOW() but not by SYSDATE(). This means that timestamp settings in the binary log have no effect on invocations of SYSDATE().
Because SYSDATE() can return different values even within the same statement, and is not affected by SET TIMESTAMP, it is nondeterministic and therefore unsafe for replication if statement-based binary logging is used. If that is a problem, you can use row-based logging.
Alternatively, you can use the --sysdate-is-now option to cause SYSDATE() to be an alias for NOW(). This works if the option is used on both the master and the slave.
The nondeterministic nature of SYSDATE() also means that indexes cannot be used for evaluating expressions that refer to it.
TIME(expr)
Extracts the time part of the time or datetime expression expr and returns it as a string.
This function is unsafe for statement-based replication. A warning is logged if you use this function when binlog_format is set to STATEMENT.
```
mysql> SELECT TIME('2003-12-31 01:02:03');
        -> '01:02:03'
mysql> SELECT TIME('2003-12-31 01:02:03.000123');
        -> '01:02:03.000123'
```
TIMEDIFF(expr1,expr2)
TIMEDIFF() returns expr1 − expr2 expressed as a time value. expr1 and expr2 are time or date-and-time expressions, but both must be of the same type.
The result returned by TIMEDIFF() is limited to the range allowed for TIME values. Alternatively, you can use either of the functions TIMESTAMPDIFF() and UNIX_TIMESTAMP(), both of which return integers.
```
mysql> SELECT TIMEDIFF('2000:01:01 00:00:00',
    ->                 '2000:01:01 00:00:00.000001');
        -> '-00:00:00.000001'
mysql> SELECT TIMEDIFF('2008-12-31 23:59:59.000001',
    ->                 '2008-12-30 01:01:01.000002');
        -> '46:58:57.999999'
```
TIMESTAMP(expr), TIMESTAMP(expr1,expr2)
With a single argument, this function returns the date or datetime expression expr as a datetime value. With two arguments, it adds the time expression expr2 to the date or datetime expression expr1 and returns the result as a datetime value.
```
mysql> SELECT TIMESTAMP('2003-12-31');
        -> '2003-12-31 00:00:00'
mysql> SELECT TIMESTAMP('2003-12-31 12:00:00','12:00:00');
        -> '2004-01-01 00:00:00'
```
TIMESTAMPADD(unit,interval,datetime_expr)
Adds the integer expression interval to the date or datetime expression datetime_expr. The unit for interval is given by the unit argument, which should be one of the following values: MICROSECOND (microseconds), SECOND, MINUTE, HOUR, DAY, WEEK, MONTH, QUARTER, or YEAR.
The unit value may be specified using one of keywords as shown, or with a prefix of SQL_TSI_. For example, DAY and SQL_TSI_DAY both are legal.
```
mysql> SELECT TIMESTAMPADD(MINUTE,1,'2003-01-02');
        -> '2003-01-02 00:01:00'
mysql> SELECT TIMESTAMPADD(WEEK,1,'2003-01-02');
        -> '2003-01-09'
```
TIMESTAMPDIFF(unit,datetime_expr1,datetime_expr2)
Returns datetime_expr2 − datetime_expr1, where datetime_expr1 and datetime_expr2 are date or datetime expressions. One expression may be a date and the other a datetime; a date value is treated as a datetime having the time part '00:00:00' where necessary. The unit for the result (an integer) is given by the unit argument. The legal values for unit are the same as those listed in the description of the TIMESTAMPADD() function.
```
mysql> SELECT TIMESTAMPDIFF(MONTH,'2003-02-01','2003-05-01');
        -> 3
mysql> SELECT TIMESTAMPDIFF(YEAR,'2002-05-01','2001-01-01');
        -> -1
mysql> SELECT TIMESTAMPDIFF(MINUTE,'2003-02-01','2003-05-01 12:05:55');
        -> 128885
```
Note

The order of the date or datetime arguments for this function is the opposite of that used with the TIMESTAMP() function when invoked with 2 arguments.
TIME_FORMAT(time,format)
This is used like the DATE_FORMAT() function, but the format string may contain format specifiers only for hours, minutes, seconds, and microseconds. Other specifiers produce a NULL value or 0.
If the time value contains an hour part that is greater than 23, the %H and %k hour format specifiers produce a value larger than the usual range of 0..23. The other hour format specifiers produce the hour value modulo 12.
```
mysql> SELECT TIME_FORMAT('100:00:00', '%H %k %h %I %l');
        -> '100 100 04 04 4'
```

TIME_TO_SEC(time)

Returns the time argument, converted to seconds.

mysql> SELECT TIME_TO_SEC('22:23:00');
        -> 80580
mysql> SELECT TIME_TO_SEC('00:39:38');
        -> 2378

TO_DAYS(date)
Given a date date, returns a day number (the number of days since year 0).
```
mysql> SELECT TO_DAYS(950501);
        -> 728779
mysql> SELECT TO_DAYS('2007-10-07');
        -> 733321
```
TO_DAYS() is not intended for use with values that precede the advent of the Gregorian calendar (1582), because it does not take into account the days that were lost when the calendar was changed. For dates before 1582 (and possibly a later year in other locales), results from this function are not reliable. See Section 13.8, “What Calendar Is Used By MySQL?”, for details.
Remember that MySQL converts two-digit year values in dates to four-digit form using the rules in Section 12.3, “Date and Time Types”. For example, '2008-10-07' and '08-10-07' are seen as identical dates:
```
mysql> SELECT TO_DAYS('2008-10-07'), TO_DAYS('08-10-07');
        -> 733687, 733687
```
In MySQL, the zero date is defined as '0000-00-00', even though this date is itself considered invalid. This means that, for '0000-00-00' and '0000-01-01', TO_DAYS() returns the values shown here:
```
mysql> SELECT TO_DAYS('0000-00-00');
+-----------------------+
| to_days('0000-00-00') |
+-----------------------+
|                  NULL |
+-----------------------+
1 row in set, 1 warning (0.00 sec)

mysql> SHOW WARNINGS;
+---------+------+----------------------------------------+
| Level   | Code | Message                                |
+---------+------+----------------------------------------+
| Warning | 1292 | Incorrect datetime value: '0000-00-00' |
+---------+------+----------------------------------------+
1 row in set (0.00 sec)


mysql> SELECT TO_DAYS('0000-01-01');
+-----------------------+
| to_days('0000-01-01') |
+-----------------------+
|                     1 |
+-----------------------+
1 row in set (0.00 sec)
```
This is true whether or not the ALLOW_INVALID_DATES SQL server mode is enabled.

TO_SECONDS(expr)

Given a date or datetime expr, returns the number of seconds since the year 0. If expr is not a valid date or datetime value, returns NULL.

mysql> SELECT TO_SECONDS(950501);
        -> 62966505600
mysql> SELECT TO_SECONDS('2009-11-29');
        -> 63426672000
mysql> SELECT TO_SECONDS('2009-11-29 13:43:32');
        -> 63426721412
mysql> SELECT TO_SECONDS( NOW() );
        -> 63426721458

Like TO_DAYS(), TO_SECONDS() is not intended for use with values that precede the advent of the Gregorian calendar (1582), because it does not take into account the days that were lost when the calendar was changed. For dates before 1582 (and possibly a later year in other locales), results from this function are not reliable. See Section 13.8, “What Calendar Is Used By MySQL?”, for details.

Like TO_DAYS(), TO_SECONDS(), converts two-digit year values in dates to four-digit form using the rules in Section 12.3, “Date and Time Types”.

In MySQL, the zero date is defined as '0000-00-00', even though this date is itself considered invalid. This means that, for '0000-00-00' and '0000-01-01', TO_SECONDS() returns the values shown here:

mysql> SELECT TO_SECONDS('0000-00-00');
+--------------------------+
| TO_SECONDS('0000-00-00') |
+--------------------------+
|                     NULL |
+--------------------------+
1 row in set, 1 warning (0.00 sec)

mysql> SHOW WARNINGS;
+---------+------+----------------------------------------+
| Level   | Code | Message                                |
+---------+------+----------------------------------------+
| Warning | 1292 | Incorrect datetime value: '0000-00-00' |
+---------+------+----------------------------------------+
1 row in set (0.00 sec)


mysql> SELECT TO_SECONDS('0000-01-01');
+--------------------------+
| TO_SECONDS('0000-01-01') |
+--------------------------+
|                    86400 |
+--------------------------+
1 row in set (0.00 sec)

This is true whether or not the ALLOW_INVALID_DATES SQL server mode is enabled.

UNIX_TIMESTAMP(), UNIX_TIMESTAMP(date)
If called with no argument, returns a Unix timestamp (seconds since '1970-01-01 00:00:00' UTC). The return value is an integer if no argument is given or the argument does not include a fractional seconds part, or DECIMAL if an argument is given that includes a fractional seconds part.
If UNIX_TIMESTAMP() is called with a date argument, it returns the value of the argument as seconds since '1970-01-01 00:00:00' UTC. date may be a DATE string, a DATETIME string, a TIMESTAMP, or a number in the format YYMMDD or YYYYMMDD, optionally including a fractional seconds part. The server interprets date as a value in the current time zone and converts it to an internal value in UTC. Clients can set their time zone as described in Section 11.6, “MySQL Server Time Zone Support”.
```
mysql> SELECT UNIX_TIMESTAMP();
        -> 1447431666
mysql> SELECT UNIX_TIMESTAMP('2015-11-13 10:20:19');
        -> 1447431619
mysql> SELECT UNIX_TIMESTAMP('2015-11-13 10:20:19.012');
        -> 1447431619.012
```
When UNIX_TIMESTAMP() is used on a TIMESTAMP column, the function returns the internal timestamp value directly, with no implicit “string-to-Unix-timestamp” conversion. If you pass an out-of-range date to UNIX_TIMESTAMP(), it returns 0.
Note: If you use UNIX_TIMESTAMP() and FROM_UNIXTIME() to convert between TIMESTAMP values and Unix timestamp values, the conversion is lossy because the mapping is not one-to-one in both directions. For example, due to conventions for local time zone changes, it is possible for two UNIX_TIMESTAMP() to map two TIMESTAMP values to the same Unix timestamp value. FROM_UNIXTIME() will map that value back to only one of the original TIMESTAMP values. Here is an example, using TIMESTAMP values in the CET time zone:
```
mysql> SELECT UNIX_TIMESTAMP('2005-03-27 03:00:00');
+---------------------------------------+
| UNIX_TIMESTAMP('2005-03-27 03:00:00') |
+---------------------------------------+
|                            1111885200 |
+---------------------------------------+
mysql> SELECT UNIX_TIMESTAMP('2005-03-27 02:00:00');
+---------------------------------------+
| UNIX_TIMESTAMP('2005-03-27 02:00:00') |
+---------------------------------------+
|                            1111885200 |
+---------------------------------------+
mysql> SELECT FROM_UNIXTIME(1111885200);
+---------------------------+
| FROM_UNIXTIME(1111885200) |
+---------------------------+
| 2005-03-27 03:00:00       |
+---------------------------+
```
If you want to subtract UNIX_TIMESTAMP() columns, you might want to cast the result to signed integers. See Section 13.10, “Cast Functions and Operators”.
UTC_DATE, UTC_DATE()
Returns the current UTC date as a value in 'YYYY-MM-DD' or YYYYMMDD format, depending on whether the function is used in a string or numeric context.
```
mysql> SELECT UTC_DATE(), UTC_DATE() + 0;
        -> '2003-08-14', 20030814
```
UTC_TIME, UTC_TIME([fsp])
Returns the current UTC time as a value in 'HH:MM:SS' or HHMMSS format, depending on whether the function is used in a string or numeric context.
If the fsp argument is given to specify a fractional seconds precision from 0 to 6, the return value includes a fractional seconds part of that many digits.
```
mysql> SELECT UTC_TIME(), UTC_TIME() + 0;
        -> '18:07:53', 180753.000000
```
UTC_TIMESTAMP, UTC_TIMESTAMP([fsp])
Returns the current UTC date and time as a value in 'YYYY-MM-DD HH:MM:SS' or YYYYMMDDHHMMSS format, depending on whether the function is used in a string or numeric context.
If the fsp argument is given to specify a fractional seconds precision from 0 to 6, the return value includes a fractional seconds part of that many digits.
```
mysql> SELECT UTC_TIMESTAMP(), UTC_TIMESTAMP() + 0;
        -> '2003-08-14 18:08:04', 20030814180804.000000
```

WEEK(date[,mode])

This function returns the week number for date. The two-argument form of WEEK() enables you to specify whether the week starts on Sunday or Monday and whether the return value should be in the range from 0 to 53 or from 1 to 53. If the mode argument is omitted, the value of the default_week_format system variable is used. See Section 6.1.5, “Server System Variables”.

The following table describes how the mode argument works.

Mode	First day of week	Range	Week 1 is the first week …
0	Sunday	0-53	with a Sunday in this year
1	Monday	0-53	with 4 or more days this year
2	Sunday	1-53	with a Sunday in this year
3	Monday	1-53	with 4 or more days this year
4	Sunday	0-53	with 4 or more days this year
5	Monday	0-53	with a Monday in this year
6	Sunday	1-53	with 4 or more days this year
7	Monday	1-53	with a Monday in this year

For mode values with a meaning of “with 4 or more days this year,” weeks are numbered according to ISO 8601:1988:

If the week containing January 1 has 4 or more days in the new year, it is week 1.
Otherwise, it is the last week of the previous year, and the next week is week 1.

mysql> SELECT WEEK('2008-02-20');
        -> 7
mysql> SELECT WEEK('2008-02-20',0);
        -> 7
mysql> SELECT WEEK('2008-02-20',1);
        -> 8
mysql> SELECT WEEK('2008-12-31',1);
        -> 53

Note that if a date falls in the last week of the previous year, MySQL returns 0 if you do not use 2, 3, 6, or 7 as the optional mode argument:

mysql> SELECT YEAR('2000-01-01'), WEEK('2000-01-01',0);
        -> 2000, 0

One might argue that WEEK() should return 52 because the given date actually occurs in the 52nd week of 1999. WEEK() returns 0 instead so that the return value is “the week number in the given year.” This makes use of the WEEK() function reliable when combined with other functions that extract a date part from a date.

If you prefer a result evaluated with respect to the year that contains the first day of the week for the given date, use 0, 2, 5, or 7 as the optional mode argument.

mysql> SELECT WEEK('2000-01-01',2);
        -> 52

Alternatively, use the YEARWEEK() function:

mysql> SELECT YEARWEEK('2000-01-01');
        -> 199952
mysql> SELECT MID(YEARWEEK('2000-01-01'),5,2);
        -> '52'

WEEKDAY(date)

Returns the weekday index for date (0 = Monday, 1 = Tuesday, … 6 = Sunday).

mysql> SELECT WEEKDAY('2008-02-03 22:23:00');
        -> 6
mysql> SELECT WEEKDAY('2007-11-06');
        -> 1

WEEKOFYEAR(date)
Returns the calendar week of the date as a number in the range from 1 to 53. WEEKOFYEAR() is a compatibility function that is equivalent to WEEK(date,3).
```
mysql> SELECT WEEKOFYEAR('2008-02-20');
        -> 8
```
YEAR(date)
Returns the year for date, in the range 1000 to 9999, or 0 for the “zero” date.
```
mysql> SELECT YEAR('1987-01-01');
        -> 1987
```
YEARWEEK(date), YEARWEEK(date,mode)
Returns year and week for a date. The year in the result may be different from the year in the date argument for the first and the last week of the year.
The mode argument works exactly like the mode argument to WEEK(). For the single-argument syntax, a mode value of 0 is used. Unlike WEEK(), the value of default_week_format does not influence YEARWEEK().
```
mysql> SELECT YEARWEEK('1987-01-01');
        -> 198652
```
Note that the week number is different from what the WEEK() function would return (0) for optional arguments 0 or 1, as WEEK() then returns the week in the context of the given year.

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User Comments

Posted by Isaac Shepard on October 11, 2003

If you're looking for generic SQL queries that will allow you to get the days, months, and years between any two given dates, you might consider using these. You just need to substitute date1 and date2 with your date expressions.

NOTE: Some of these formulas are complex because they account for all cases where date1 < date2, date1 = date2, and date1 > date2. Additionally, these formulas can be used in very generic queries where aliases and temporary variables are not allowed.

Number of days between date1 and date2:

TO_DAYS(date2) - TO_DAYS(date1)

Number of months between date1 and date2:

IF((((YEAR(date2) - 1) * 12 + MONTH(date2)) - ((YEAR(date1) - 1) * 12 + MONTH(date1))) > 0, (((YEAR(date2) - 1) * 12 + MONTH(date2)) - ((YEAR(date1) - 1) * 12 + MONTH(date1))) - (MID(date2, 9, 2) < MID(date1, 9, 2)), IF((((YEAR(date2) - 1) * 12 + MONTH(date2)) - ((YEAR(date1) - 1) * 12 + MONTH(date1))) < 0, (((YEAR(date2) - 1) * 12 + MONTH(date2)) - ((YEAR(date1) - 1) * 12 + MONTH(date1))) + (MID(date1, 9, 2) < MID(date2, 9, 2)), (((YEAR(date2) - 1) * 12 + MONTH(date2)) - ((YEAR(date1) - 1) * 12 + MONTH(date1)))))

Number of years between date1 and date2:

IF((YEAR(date2) - YEAR(date1)) > 0, (YEAR(date2) - YEAR(date1)) - (MID(date2, 6, 5) < MID(date1, 6, 5)), IF((YEAR(date2) - YEAR(date1)) < 0, (YEAR(date2) - YEAR(date1)) + (MID(date1, 6, 5) < MID(date2, 6, 5)), (YEAR(date2) - YEAR(date1))))

Now for some comments about these.

1. These results return integer number of years, months, and days. They are "floored." Thus, 1.4 days would display as 1 day, and 13.9 years would display as 13 years. Likewise, -1.4 years would display as -1 year, and -13.9 months would display as -13 months.

2. Note that I use boolean expressions in many cases. Because boolean expressions evaluate to 0 or 1, I can use them to subtract or add 1 from the total based on a condition.

For example, to calculate the number of years between to dates, first simply subtract the years. The problem is that doing so isn't always correct. Consider the number of years between July 1, 1950 and May 1, 1952. Technically, there is only one full year between them. On July 1, 1952 and later, there will be two years. Therefore, you should subtract one year in case the date hasn't yet reached a full year. This is done by checking the if the second month-day is before the first month-
day. If so, this results in a value of 1, which is subtracted from the total. The IF statements are in the formula because we must add one year when dealing with the dates in the opposite order, and we must not add or subtract anything when the difference of the date years is zero.

3. To get the month-day, I use MID. This is better
than using RIGHT, since it will work for both dates
and datetimes.

4. Unlike many other solutions, these queries should
work with dates prior to 01/01/1970.

Posted by on February 6, 2003

Spent some time trying to work out how to calculate the month start x months ago ( so that I can create historical stats on the fly)

here is what I came up with..

((PERIOD_ADD(EXTRACT(YEAR_MONTH FROM CURDATE()),-6)*100)+1)

this gives you the first day of the month six months before the start of the current month in datetime format

Posted by filip wolak on August 4, 2003

Several times i have come to a followng date/time problem:
In the table i am storing both date and time information in the datetime column. Querying, I want to receive COUNTed results grouped by date, and not date and time. I came to the easy solution:
SELECT DATE_FORMAT(postdate, '%Y-%m-%d') AS dd, COUNT(id) FROM MyTable GROUP BY dd;

I suppose this solution to be quite slow (date formatting).

Later, i 'upgraded' this query to use the string function:
SELECT substring(postdate, 1,10) AS dd, COUNT(id) FROM MyTable GROUP BY dd;

knowing, that the result is in the fixed format. Works faster.

Posted by Stoyan Stefanov on August 16, 2003

Hope this will help somebody. The way I found to sum time:
SELECT SEC_TO_TIME( SUM( TIME_TO_SEC( `time` ) ) ) AS total_time FROM time_table;

Posted by Gerard Manko on December 17, 2003

Comparing Dates when using MS Access and MyODBC

If you are using MS Access and have created Access queries to substitute for views (which are not yet available in mySQL), you can use the following syntax ro perform date comparisons and avoid the dreaded "ODBC -- call failed" error:

Select * from [Task Effort Summary]
Where ((Date() + 0) > CLng([Task Effort Summary].[s_end]))

This particular example retuns tasks that are overdue (where todays date is past the scheduled end date). This query was developed for reports on a TUTOS database.

Posted by on January 9, 2004

Note that the built-in default values for the DATE and DATEFIELD column types is out of range. For example, 0000-00-00 is a valid way of expressing NULL, but if the column is set as NOT NULL, 0000-00-00 is still the default value. This can cause problems with some applications using MySQL.

Posted by asdacfd dsfdsf on January 27, 2004

I was looking for a function to detect if the current week is odd or even. I could not find one so I use this:
MOD((DATE_FORMAT(CURDATE(),"%v")),2)
The output is a '0'(even) or a '1'(odd)

Posted by Steve West on February 15, 2004

To create a DATETIME of NOW() in UTC without upgrading to 4.1.1, just use:

DATE_ADD( '1970-01-01', INTERVAL UNIX_TIMESTAMP() SECOND )

Posted by on March 4, 2004

workaround for STR_TO_DATE pre version 4.1.1. ugly but it seems to work fine.

assumption: you know the format of the received date (in the below example the format is mm/dd/yy, m/d/yy, mm/dd/yyyy, etc)

the statement extracts the year by locating the index of the second '/' and reading from the right of the string to that index. the index of the second is '/' is found by using LOCATE with the index of the first '/'.
it extracts the day by locating the indeces of the first and second '/' and reading between them
it extracts the month by locating the index of the first '/' and reading from the left of the string to that index.
it then CONCATs the year month and day pieces together separating them with hyphens.
lastly, it lets DATE_FORMAT do its magic on the string.

(replace the test string '1/11/03' with your field name, etc)

select DATE_FORMAT( CONCAT( RIGHT( '1/11/03' , length( '1/11/03') - LOCATE('/', '1/11/03' , LOCATE('/', '1/11/03' ) + 1 ) ) , '-' , LEFT( '1/11/03' , LOCATE('/', '1/11/03' ) - 1 ) , '-', SUBSTRING( '1/11/03' , LOCATE('/', '1/11/03' ) + 1, LOCATE('/', '1/11/03' , LOCATE('/', '1/11/03' ) + 1 ) - LOCATE('/', '1/11/03' ) - 1 ) ) , '%Y-%m-%d' )

Posted by Olav Alexander Mjelde on March 15, 2004

Lets say you have the mysql before 4.1.1 (where timediff() was implementet), and you want to do a timediff.

I wanted to make a "active users" on my page, but I found out that I didnt have the timediff function (to find persons which have been active within 5 minutes).

So, I figured this query out:

SELECT nick FROM `users` WHERE TO_DAYS( NOW( ) ) - TO_DAYS( last_login ) <=1 AND DATE_FORMAT( CURRENT_TIMESTAMP( ) , '%H%i' ) - DATE_FORMAT( last_login, '%H%i' ) <=5 ORDER BY `nick` ASC;

it selects the field nick (which is the only one to be displayd) and then it filters for 1 day or less in age of activity. after that, it filters for 5 minutes or less in activity.

first you need to filter away the other days, or your script might get fooled to think that yesterdays login was todays.

I'm currently using this, and it works fine!
on the other page, you of course need to update the timestamp field (when session excists, on reload)

Posted by Cherice Scharf on April 5, 2004

Here is an example to convert various user inputs for a date field on an ASP page (VBScript) that will convert common formats (i.e., m/d/yy, mm/dd/yyyy, etc.) to MySQL database format of (yyyy-mm-dd). The function begins by establishing that there is a date in the field. Then splits the date (converted to string) into three parts by locating "/". DateArray(0), DateArray(1), DateArray(2) hold the month, day and year, respectively. These are then checked for the amount of digits, if there are not enough digits in month or day then a leading zero is added. If there are only two digits on the year (ie "04") then a leading "20" is added.

Function ConvertInputDate(varDate)

If (Len(Trim(varDate)) > 0) Then
DateArray=Split(CStr(varDate),"/")

IF Len(Trim(DateArray(0))) < 2 Then
DateArray(0) = "0" & DateArray(0)
End If

If Len(Trim(DateArray(1))) < 2 Then
DateArray(1) = "0" & DateArray(1)
End If

If Len(Trim(DateArray(2))) < 4 Then DateArray(2) = "20" & DateArray(2)
End If

varDate = DateArray(2) & "-" & DateArray(0) & "-" & DateArray(1)

End If

End Function

*Please note if a user does not use two slashes this function will not work. It is best to indicate "mm/dd/yy" near the label on the page. It will take 4/6/04, 10/6/04, 3/16/2004 and all combinations with two slashes.

Posted by Jason Richard on April 9, 2004

I had a problem with my login script using PHP and MySQL when daylight savings time (DST) came around this year.

I was using MYSQL NOW() function to add the current date and time to the user's record into a datetime field. When DST came into effect newly entered login times were an hour slow (I'm in EST). Since the last login is to be updated only if an hour or more has passed since the last login this was a big problem!

The problem is that PHP takes DST into account and MySQL does not (as far as I know) and I was entering the time using MySQL's NOW() function and then comparing the value returned by PHP's time() function.

A very simple solution to this is the following. Note the PHP time format string 'YmdHis' - it formats to YYYYMMDDHHMMSS which is what MySQL expects for a date/time field.

$now = time();
$lastLogin = strtotime($row['lastLogin']);
$diff = $now - $lastLogin;
$now = date('YmdHis',$now)

if($diff > 3600) { // 3600 seconds is 1 hour
$query = 'UPDATE members SET logins = logins + 1, lastLogin = '.$now.' WHERE memberID = '.$SEC_ID;
mysql_query($query);
}

Now the date entered is the PHP time (that accounts for DST) and we are comparing it to PHP time so all is well.

I think this approach will work well for any time you wish to enter a date into MySQL using PHP. Just format the date using the "YmdHis" format string and use the strtotime() function to read a date retrieved from MySQL.

The advantage to this approach rather than just entering the "normal" PHP date into a char or text field is that the dates are "human" readable in the table and all the MySQL date/time functions are available for future queries.

Posted by Martin Schwedes on April 25, 2004

to localize the weekday:
SELECT ELT( WEEKDAY('2004-04-10')+1, 'Montag','Dienstag','Mittwoch','Donnerstag','Freitag','Samstag','Sonntag');

long version with month:
SELECT DATE_FORMAT( '2004-04-10', CONCAT( ELT( WEEKDAY('2004-04-10')+1, 'Montag','Dienstag','Mittwoch','Donnerstag','Freitag','Samstag','Sonntag'),', %d. ', ELT( MONTH('2004-04-10'), 'Januar','Februar','März','April','Mai','Juni','Juli','August','September','Oktober','November','Dezember'),' %Y'));
--> Samstag, 10. April 2004

same for unix-timestamp:
SELECT DATE_FORMAT( FROM_UNIXTIME(1081548000), CONCAT( ELT( WEEKDAY(FROM_UNIXTIME(1081548000))+1, 'Mo','Di','Mi','Do','Fr','Sa','So'),', %d. ', ELT( MONTH(FROM_UNIXTIME(1081548000)), 'Jan.','Feb.','März','April','Mai','Juni','Juli','Aug.','Sept.','Okt.','Nov.','Dez.'),' %Y'));
--> Sa, 10. April 2004

Posted by Philippe Poelvoorde on April 30, 2004

I had to query a table and retrieve rows that were added only today, so :

select id from my_table
where
timestamp < date_format(date_add(CURRENT_TIMESTAMP(), interval 1 day),'%Y%m%d000000')
AND
timestamp >= date_format(CURRENT_TIMESTAMP(),'%Y%m%d000000')

starting with MySQL 4.0, you could also use the BETWEEN ... AND syntax.
If anyone has a better query to do that, let me know.

Posted by Michael Marcus on May 1, 2004

After reading numerous articles and posts regarding converting back and forth between SQL datetime and VBscript datetime, I opted for the simplest solution for my databases. I simply save all datetime values in varchar(20) fields and call on either MySQL or VBscript functions to get datetime values or check/convert datetime values. For example:

currentDT = CStr(cn.execute("SELECT NOW()").Fields(0).Value)

will fetch current datetime in the SQL server's datetime format and then convert it to a string. [Obviously, cn is set by Set cn = Server.CreateObject("ADODB.Connection") to create the database connection, then the database is opened with a cn.open (parameters).]

You can then save this string to an appropriate field such as 'flddate_added' which is formatted as varchar(20).

When retrieving the flddate_added value, you can use this VBscript code to check if the value is indeed a datetime value and convert it to the datetime format of the user's computer"

if IsDate(flddate_added) then
=CDate(flddate_added) ' convert to user's system format for display using user's codepage
else
=flddate_added ' just display the string
end if

The above methods allow me to get around all of the issues regarding VBscript's datetime display format differences depending on the system local.

Posted by Ray Morris on July 15, 2004

Posted by Filip Wolak:

> Several times i have come to a followng date/time problem:
> In the table i am storing both date and time information in the datetime
> column. Querying, I want to receive COUNTed results grouped by date,
> and not date and time.
...
> SELECT substring(postdate, 1,10) ...

If it's a DATETIME column than substring is not appropriate -
it's logically nonsensical of course, and just happens to work
in some version of MySQL because the DATETIME happens
to be represented by a string in some contexts.
Better would be to treat the DATETIME as a DATETIME
rather than as a string, which will work in future versions
of MYSQL and in other RDMS:
SELECT DATE(postdate) ...

Posted by David Lyon on July 17, 2004

Here is another VB/ASP function for converting Dates from standard to MySQL format. Cherise gave a nice example above, but it has extra complexity due to the use of arrays and also may be proned to user input errors.

The following example will work based on the Localization settings of the server on which it is run. So it shouldn't care whether the date is dd-mm-yyyy, mm/dd/yy, mm/dd/yyyy, m-d-yy, etc. Just make sure you pass it a date value that is formatted compliant to the server's localization. If necessary use VB's CDate(strDateValue) before passing strDateValue to the function.

You can also easily modify this function to do the same for Time values, except you use Hour, Minute, and Second VB functions, and delimit with a colon (:) instead of a dash (-).

Hope this helps!

Function funcMySqlDate(dtmChangeDate)
'CONVERTS LOCALIZED DATE FORMAT (for example: m/d/yy) TO MySQL FORMAT (yyyy-mm-dd)
Dim strTempYear, strTempMonth, strTempDay
strTempYear = Year(dtmChangeDate)
strTempMonth = Month(dtmChangeDate)
strTempDay = Day(dtmChangeDate)

if Len(strTempYear) = 2 then 'Y2K TEST - 1938-2037 - ADJUST AS NECESSARY
if strTempYear >= 38 then
strTempYear = "19" & strTempYear
else
strTempYear = "20" & strTempYear
end if
end if
if strTempMonth < 10 then strTempMonth = "0" & strTempMonth
if strTempDay < 10 then strTempDay = "0" & strTempDay

funcMySqlDate = strTempYear & "-" & strTempMonth & "-" & strTempDay
End Function

Posted by Benjamin Zagel on August 5, 2004

To find out the last day of a month use:

SELECT (DATE_FORMAT('2004-01-20' ,'%Y-%m-01') - INTERVAL 1 DAY) + INTERVAL 1 MONTH;

It tooks me a few time to have this idea, but it works. If you want to have the first day of a month use:

SELECT DATE_FORMAT('2004-01-20' ,'%Y-%m-01');

To find out the first day of a month was my first development step, then it was easy to extract the last day of a month. It is usefull for accounting for services where I need this solution.

Greetings

Posted by Mark Stafford on August 6, 2004

I see the use for both, but I find this layout more useful as a reference tool:

+--------------+----------+--------------------+
| metric       | variant  | result             |
+--------------+----------+--------------------+
| microseconds | %f       | 000000..999999     |
| seconds      | %s or %S | 00..59             |
| minutes      | %i       | 00..59             |
| hours        | %H       | 00...23            |
|              | %h or %I | 00...12            |
|              | %k       | 0...23             |
|              | %l       | 1...12             |
| day          | %a       | Sun...Sat          |
|              | %D       | 1st, 2nd, 3rd      |
|              | %d       | 0.31               |
|              | %e       | 0..31              |
|              | %j       | 001...366          |
|              | %W       | Sunday...Sat       |
|              | %w       | 0...6              |
| week         | %U       | 00...53 per Sun    |
|              | %u       | 00...53 per Mon    |
| *            | %V       | 01...53 per Sun    |
| *            | %v       | 01...53 per Mon    |
| month        | %b       | Jan...Dec          |
|              | %c       | 0...12             |
|              | %M       | January...December |
|              | %m       | 00...12            |
| year         | %Y       | 1999               |
|              | %y       | 99                 |
| *            | %X       | 1999               |
| *            | %x       | 99                 |
| time         | %r       | 01:31:12 pm        |
|              |          | %T | 01:31:12 pm   |
|              | %p       | AM or PM           |
| Percent sign | %%       | %                  |
+--------------+----------+--------------------+

Posted by M l on August 7, 2004

Select records that are older than X days from the current date where sent_time is a Timestamp datatype field.

select ID from MESSAGE where SENT_TIME < (CURDATE() - INTERVAL 5 DAY);

Posted by R C on August 24, 2004

If you do not have 4.xx yet here is a simple way to get the last day of the month. You can replace the current date with a var to find the last day of any month.

SELECT
SUBDATE( ADDDATE( CURDATE(), INTERVAL 1 MONTH), INTERVAL DAYOFMONTH( CURDATE() ) DAY) AS LAST_DAY_MONTH

seems to work well .

Posted by Martin Algesten on September 9, 2004

>Several times i have come to a followng date/time problem:
>In the table i am storing both date and time information in the
>datetime column. Querying, I want to receive COUNTed results
>grouped by date, and not date and time. I came to the easy
>solution:

I needed a query for a more general case to do time based reporting on arbitrary big "slices" of timestamped data.

My table has a column 'timestamp' which is of type 'datetime'.

The following makes '120' second big slices

select from_unixtime(unix_timestamp(timestamp) - unix_timestamp(timestamp) % 120) as slice, ... group by slice;

Posted by David Berry on September 17, 2004

I wanted to find the start date (Sunday) and the end date (Saturday) for any given week when all I had to go from is an arbitrary date (more precisely, the current date). Since MySQL registers Sunday as 1, and Saturday as 7, if you wish to adjust the start and end points on a week, you'll have to modify the following function calls appropriately, and change the integers, or (as I have done) use variables:

set @someday = curdate();
set @weekstart = 1; // Sunday
set @weekend = 7; // Saturday

end of week:
select date_add(@someday, interval @weekend-dayofweek(@someday) day);

beginning of week:
select date_sub(@someday, interval dayofweek(@someday)-@weekstart day);

Of course, I use these functions in a more complex query that filters select results from a table with a "datetime" field. This allows me to focus on weekly data. A very neat thing is being able to replace 'curdate()' with a date at (theoretically) any point in time on the Gregorian calendar.

Posted by Jeffrey Friedl on October 31, 2004

The value returned by

UNIX_TIMESTAMP(NOW())

can be quite unintuitive during the last hour of daylight-saving time in the fall, as it can return a timestamp that's an hour ahead of the current time. (The docs indicate that this may be "fixed" from 4.1.3, but I have not tested.)

This is because CST-related information is lost during the conversion by NOW() from the current time to a string. When presented a date string like "2004-10-31 01:52:37" which names a time that happened twice (once during daylight-saving time, and again an hour later in standard time), it doesn't know which you intend it to be interpreted as.

The docs indicate that from 4.1.3, it uses the timezone in effect at the time of the SELECT, which implies that

FROM_UNIXTIME("2004-10-31 01:52:37")

returns a different value depending on whether you are currently under daylight-saving time or not. With 4.1.2 and before, it seems to always use standard time, and hence the one-hour "error" (which is not really an error, but damn unintuitive that UNIX_TIMESTAMP(NOW()) does not return the UNIX_TIMESTAMP for now.

Note that UNIX_TIMESTAMP() without args does return the proper unix timestamp for the current time.

Posted by Shamun toha on December 18, 2004

If you have a table1 , and (fields date which is varchar(100)
you can also convert it as date type look the following example

mysql> select str_to_date(date,'%d/%m/%Y') as Mydate from table1 order by Mydate DESC;

+------------+
| Mydate     |
+------------+
| 2004-12-16 |
| 2004-12-15 |
| 2004-12-02 |
| 2004-12-02 |
| 2004-11-01 |
| 2004-10-29 |
| 2004-10-12 |
| 2004-10-07 |
| 2004-09-12 |
| 2004-08-19 |
| 2004-08-13 |
| 2004-08-09 |
| 2004-08-04 |
| 2004-07-30 |
| 2004-07-26 |
| 2004-07-20 |
| 2004-07-16 |
| 2004-07-14 |
+------------+

18 rows in set (0.00 sec)

mysql>

Posted by John Romano on January 26, 2005

If you need to EXTRACT the QUARTER prior to v5.0 try CEILING(EXTRACT(MONTH FROM date)/3)

Posted by Robert Christiaanse on January 27, 2005

CALCULATING A DATE USING A WEEK NUMBER

If you want to calculate the date having a year, a day of the week and a weeknumber (Let's say Thursday of week number 4 in 2005), you can calculate it like this:

SELECT DATE_ADD('2005-01-04', INTERVAL ((4-1)*7+(4 - DATE_FORMAT('2005-01-04','%w'))) DAY);

In PHP it would be something like this (when weeks start on Monday):

$Days=array('xx','ma','di','wo','do','vr','za','zo');
$DayOfWeek=array_search($aDay,$Days); //get day of week (1=Monday)
$Year=2005;
$Week=4;

$query = "SELECT DATE_ADD('".$Year."-01-04', INTERVAL ((".$Week."-1)*7+(".$DayOfWeek." - DATE_FORMAT('".$Year."-01-04','%w'))) DAY)";

January 4th is chosen as a base, because it is always in week number 1. ( January 1st is not necessarely in week1! )

You can test it with this:


<?php

//connect to your database first

$Year=2005;
for ($weeknr=0; $weeknr <= 53; $weeknr++)
{
  for ($day=1; $day <= 7; $day++)
  {
    $query = "
      SELECT 
         DATE_ADD('".$Year."-01-04', 
                        INTERVAL ((".$weeknr."-1)*7+
                        (".$day." - DATE_FORMAT('".$Year."-01-04','%w'))) DAY)
     ";
      $result= mysql_query($query);
      if ($result)
      {
          $row = mysql_fetch_row($result); 
        echo "year=$Year weekno=$weeknr day=$day : ".$row[0].'<br>';
      }
      else
        echo 'empty result set<br>'.EOL;
   }
}  

?>

Posted by Ralph Noordanus on February 18, 2005

+---------------------+---------------------+
| date1               | NOW()               |
+---------------------+---------------------+
| 2005-03-17 16:00:00 | 2005-02-18 13:07:29 |
+---------------------+---------------------+

If you're looking for an SQL query that returns the number of days, hours and minutes between date1 and now:

SELECT CONCAT(DAYOFYEAR(date1)-DAYOFYEAR(NOW()),' days ', DATE_FORMAT(ADDTIME("2000-00-00 00:00:00",SEC_TO_TIME(TIME_TO_SEC(date1)-TIME_TO_SEC(NOW()))),'%k hours and %i minutes')) AS time FROM time_table;

+---------------------------------+
| time                            |
+---------------------------------+
| 27 days 2 hours and 52 minutes  |
+---------------------------------+

Posted by Luke Burgess on October 15, 2006

There doesn't appear to be an official way of selecting * from a table where eg 'date is january 2005'. So far i've found 8 different ways!!

1. where date like '2005-01-%'
2. where DATE_FORMAT(date,'%Y-%m')='2005-01'
3. where EXTRACT(YEAR_MONTH FROM date)='200501'
4. where YEAR(date)='2005' and MONTH(date)='1'
5. where substring(date,1,7)='2005-01'
6. where date between '2005-01-01' and '2005-01-31'
7. where date >= '2005-01-01' and date <= '2005-01-31'
8. where date IN('2005-01-01', '2005-01-02', '2005-01-03', '2005-01-04', '2005-01-05', '2005-01-06', '2005-01-07', '2005-01-08', '2005-01-09', '2005-01-10', '2005-01-11', '2005-01-12', '2005-01-13', '2005-01-14', '2005-01-15', '2005-01-16', '2005-01-17', '2005-01-18', '2005-01-19', '2005-01-20', '2005-01-21', '2005-01-22', '2005-01-23', '2005-01-24', '2005-01-25', '2005-01-26', '2005-01-27', '2005-01-28', '2005-01-29', '2005-01-30', '2005-01-31')

Posted by Josh Hayden on March 20, 2005

I needed a query that would delete all rows that were created over an hour ago. Here's what I used:

To insert the row:
INSERT INTO `table_name` ( `time_col`) VALUES (NOW());

To delete the rows created over an hour ago:
DELETE FROM `table_name` WHERE `time_col` < ADDDATE(NOW(), INTERVAL -1HOUR);

Posted by Erin Quick-Laughlin on March 29, 2005

To take Cherice Scharf's vb example one step further, here's the conversion from vb's now format of 'MM/DD/YY HH:MM:SS PM' to 'YYYY-MM-DD HH:MM:SS' for easy insertion to the datetime field:

Function ConvertInputDateTime(varDateTime)

If (Len(Trim(varDateTime)) > 0) Then
DateTimeArray=Split(CStr(varDateTime)," ")

varDate = DateTimeArray(0)
varTime = DateTimeArray(1)
varAMPM = DateTimeArray(2)

If (Len(Trim(varDate)) > 0) Then
DateArray=Split(CStr(varDate),"/")

IF Len(Trim(DateArray(0))) < 2 Then
DateArray(0) = "0" & DateArray(0)
End If

If Len(Trim(DateArray(1))) < 2 Then
DateArray(1) = "0" & DateArray(1)
End If

If Len(Trim(DateArray(2))) < 4 Then
DateArray(2) = "20" & DateArray(2)
End If

varDate = DateArray(2) & "-" & DateArray(0) & "-" & DateArray(1)

End If

If (Len(Trim(varDate)) > 0) Then
TimeArray=Split(CStr(varTime),":")

If Trim(varAMPM) = "PM" Then
TimeArray(0) = CStr(TimeArray(0) + 12)
End If

If Len(Trim(TimeArray(0))) < 2 Then
TimeArray(0) = "0" & TimeArray(0)
End If

varTime = TimeArray(0) & ":" & TimeArray(1) & ":" & TimeArray(2)

End If

varDateTime = varDate & " " & varTime

End If

ConvertInputDateTime = varDateTime

End Function

Thanks for the starting code Cherice!

Posted by paul adams on April 1, 2005

"SELECT id, transactionid, (UNIX_TIMESTAMP(now()) - UNIX_TIMESTAMP(date)) AS date , sucessful, amount FROM Transaction where sucessful = 1"

to work out the difference between when it was placed to now.

Posted by santi bari on June 10, 2005

GENERATE missing days on a table with date gaps
=====================================

If you want to bring visits per day to your site and you have a table
wich
is storing the hits, in a way similar to this...

+--------------+--------------------------+
|  date        | IP                    
+--------------+--------------------------+
|2004-8-3      |  123.123.124.155
|2004-8-3      |  123.123.124.145
|2004-8-5      |  123.123.124.145
+--------------+--------------------------+

You may want to draw a chart and retrieve all the hits per day. The
problem is that DAYS WITHOUT HITS WON'T APPEAR. And you won't be able
to
display the info of '0 hits'.

One solution to this which is easy to code and clean, is to create and
have in your database, a table named 'calendar' with all the days from
today till some years from now (let's say, till 2034). The table
should
look something like this:

+----------+
| date
+----------+
| 2004-1-1
| 2004-1-2
| 2004-1-3
| 2004-1-4
| 2004-1-5
|   ...
| etc...
+---------+

Here is a piece of code which will make such table:


<?php

mysql_query("CREATE TABLE `calendar` (
  `id` int(11) NOT NULL auto_increment,
  `date` date NOT NULL default '0000-00-00',
  PRIMARY KEY  (`id`)
) TYPE=MyISAM; ");

for($i=0;$i<=(365*30);$i++)
    mysql_query("INSERT INTO CALENDAR SET date=date_add(now(),INTERVAL 
LAST_INSERT_ID() DAY)");

?>

Then all you have to do is perform a LEFT JOIN from this table and
you've
got every day from the period of time you specify. Even those with 0
hits

SELECT calendar.date, count(*)
FROM calendar
LEFT JOIN visits ON calendar.date=visits.date
GROUP BY calendar.date

Posted by Benjamin Gehrels on May 12, 2005

Be carefull with the DAYOFYEAR-Function in comparisions, because you will run into a trap every 4 years, when Feburary is a day shorter...

Posted by Labb on May 20, 2005

To Posted by Erin Quick-Laughlin on March 29 2005 2:49am

The much more easier way:

date = "YYYY/MM/DD HH-SS-MM"
date = Replace(date, "/", "-")

thats it...

Posted by Juan Sanjuan on May 23, 2005

age from date of birth compared whith
in this function you can know the age of a person(it works for my). preg 12 is a date in the format show bellow i dont know if it is fast. if you have a recent version you can asign curtime to a variable for get more performance else use php,c++ or another to save it as:
YYYY-MM-DD example: 1997-03-31
left((curtime()-preg12),(CHAR_LENGTH(curtime()-preg12)-4))
another way is:
(TO_DAYS("a - date") - TO_DAYS("birth"))/365
you can replece the curdate for a before date changing curdate to this 20000619 NOT THIS: 2000-06-19 if you have beter way send it to my tanks bye.

Posted by John Anderson on May 25, 2005

To calculate week ending date given an arbitrary date, use the following (assumes Saturday is week end)

SELECT DATE_ADD('2005-05-24', INTERVAL (7 - DAYOFWEEK('2005-05-24')) DAY)

SELECT DATE_ADD(table.column, INTERVAL (7 - DAYOFWEEK(table.column)) DAY)

Posted by Pe3k on June 15, 2005

If U have older version of MySQL you can replace 'TIMEDIFF(time1,time2)' with
'SEC_TO_TIME( (TO_DAYS(time1)*24*3600+TIME_TO_SEC(time1)) - (TO_DAYS(time2)*24*3600+TIME_TO_SEC(time2)) )'

It is completly same. :)

Posted by Daniel Schroeder on July 16, 2005

I had the task to select rows of a table where the date of creation was in the future of a given date.
The problem was there was no date or timestamp-field, but two fields (int), one for month and one for year.
Since I have MySQL-Version prior to 4.1.1, where most of the nice date/time-functions have been added, I had to work out a query that builds and compares dates out of the given values.

Here it is:

SELECT *
FROM your_table
WHERE CONCAT(your_table.field_year,'-',REPEAT(0,2-LENGTH(your_table.field_month)),your_table.field_month,'-','01') >= CONCAT({MIN_YEAR},'-',REPEAT(0,2-LENGTH({MIN_MONTH})),{MIN_MONTH},'-','01')
ORDER BY your_table.field_year,
your_table.field_month;

I noticed an advantage compared to working with timestamps: You are able to work with dates before 1970.

Posted by Oliver Pereira on July 19, 2005

The description of FROM_DAYS(N) - "Given a daynumber N, returns a DATE value" - uses the term "daynumber" without explaining it.

The description of TO_DAYS(date) - "Given a date date, returns a daynumber (the number of days since year 0)" - lower down the page at least tries to explain the term, but unsuccessfully.

There are two problems here. Firstly, there was no year 0 in the Gregorian calendar. Secondly, a number of days has to be counted from a day, not a year. Do they mean the beginning of the (non-existent) year, or the end of the (non-existent) year? Do non-existent years even have beginnings and ends? Someone should amend these descriptions.

Posted by k s on August 12, 2005

Here's another query to get the number of months between two dates:
select period_diff(DATE_FORMAT(date1,'%Y%m'),DATE_FORMAT(date2,'%Y%m')) from tablexy

Posted by Bob Terrell on August 22, 2005

Note that there is currently no way to get the 'AM' or 'PM' part of a time-only value using the built-in functions. You must first convert it to a datetime and then use DATE_FORMAT('%p') or perform your own calculations in your app.

Posted by Deron Meranda on August 31, 2005

On transactional consistency...Concerning the functions which use the real current time, such as NOW(), the manual says "Functions that return the current date or time each are evaluated only once per query at the start of query execution."

Note though that this does not apply across entire transactions, as you may expect. Thus a transaction like:

START TRANSACTION;
INSERT INTO EVENTS VALUES (NOW(), 'A');
INSERT INTO EVENTS VALUES (NOW(), 'B');
COMMIT;

will result in potentially two different times being recorded for the two records.

Posted by cameron green on September 16, 2005

If you need the type to be dynamically taken from a table (that is where you have "year", "day", "month" etc as a column in the table), here is the best way I could work out to do it. Expand as necessary :

SELECT set_date, unit_period, unit_multiplier, CASE WHEN unit_period = "month" THEN DATE_SUB(set_date, INTERVAL unit_multiplier MONTH) WHEN unit_period = "week" THEN DATE_SUB(set_date, INTERVAL (unit_multiplier * 7) DAY) WHEN unit_period = "year" THEN DATE_SUB(set_date, INTERVAL unit_multiplier YEAR) ELSE DATE_SUB(set_date, INTERVAL unit_multiplier DAY) END FROM dates_table;

Posted by Andrzej Salamon on September 22, 2005

Returns all rows from actual month to given @months. eg. if you want get all rows in:

5 months from now:
(2005-09) - 5 = (2005-04)
all rows from 2005-04-01 to 2005-04-30

2 months from now
(2005-09) - 2 = (2005-07)
all rows from 2005-07-01 to 2005-07-31

SQL variables, can be PHP variables like $months,$nextMonth,$begin,$end

set @months = 1; #change only this value(months back from actual month)
set @nextMonth = @months+1;

set @begin = FROM_DAYS(TO_DAYS(LAST_DAY( DATE_SUB(NOW(), INTERVAL @nextMonth MONTH )))+1);

set @end = FROM_DAYS(TO_DAYS(LAST_DAY( DATE_SUB(NOW(), INTERVAL @months MONTH )))+1);

SELECT cols_u_want FROM tbl_u_want
WHERE timestampCol
BETWEEN @begin AND @end

It`s my solution. If U have Your own please email me.
Sorry for my english :)

Posted by Bryan Donovan on November 14, 2005

I'm not sure if this is the best way, but it works to get the date of the Monday of the week of a date. For example, if you have a datetime column called starttime in a table called test_events, you could select the distinct Mondays from your table as follows:

SELECT DISTINCT(STR_TO_DATE(CONCAT(YEARWEEK(starttime),'1'),'%x%v%w'))
FROM test_events;

Hopefully there is a better way..

Posted by Rodolfo Maripan on November 29, 2005

I was using mysql v4 and the date was in a varchar data type, in order to change the data type in mysql v5 i use the following code:

update ssd_escondida.tactual_sag4 set ssd_escondida.tactual_sag4.Fecha=str_to_date(ssd_escondida.tactual_sag4.Fecha2,'%e/%m/%Y');

where:

ssd_escondida: database
tactual_sag4:is a table
Fecha: is a date type
Fecha2:is a varchar which contains a date, but is from 01/01/2005 to 04/01/2005 (with a zero at the begining)

why i used %e instead of %d??? the answer is very simple, there is a problem with de help about str_to_date:
%d: represents the days, but from 0 to 31 and...
%e: represents the days, but from 00 to 31.
that's the reason why we cannot use: str_to_date('00/00/0000',%d/%m/%Y), we must use str_to_date('00/00/0000','%e/%m/%Y')
Another way in order to change a string like: 00/00/0000 to a date is to use: str_to_date('00/00/0000','0%d/%m/%Y')

Posted by Regina Mullen on December 3, 2005

Simple method of converting dates from any of
MM-DD-YYYY
MM/DD/YYYY
MM.DD.YYYY
(oldDate) to YYYY-MM-DD (addDate). Load date in as text and convert in one go using:

<code>
update table set addDate = CONCAT_WS('-', RIGHT( oldDate,4), LEFT( oldDate,2), SUBSTRING( oldDate,4,2))
</code>

Caveat: make sure your text input doesn't have spaces.

Posted by Hyper Hacker on December 26, 2005

In MySQL 4.0, and possibly others, UNIX_TIMESTAMP() doesn't work with dates before 1970. This query does the same, and works with any date from from Fri, 13 Dec 1901 20:45:54 to Tue, 19 Jan 2038 03:14:07. 'date' is the name of the DATETIME column you need a timestamp of.

SELECT (((TO_DAYS(date) * 86400) + TIME_TO_SEC(date)) - (TO_DAYS("1970-01-01") * 86400)) AS timestamp

If you're using PHP, note that date() accounts for DST and thus may appear to return incorrect results; also, don't forget to escape the quotes around 1970-01-01.

Posted by Noel Athaide on December 27, 2005

Keyphrases: Birthday reminder, select dates between

This might be useful. If you have a database containing 'name' and 'birthday' (as columns) then the following query will list the birthdays in the next 15 days. (16 to be more precise :-))

What I found unique about this problem is that the YEAR (of birth) will always be different and hence one cannot simply use a query like :

|   SELECT * FROM `friends` WHERE 
|   `birthday` >= CURDATE() 
|   AND 
|   `birthday` <= ADDDATE(CURDATE(), INTERVAL 15 DAY);

because it would take the year into consideration.

The correct way, I believe, to get the desired result is as follows:

|   SELECT * FROM `friends` WHERE (
|   EXTRACT(MONTH FROM `birthday` ) = EXTRACT(MONTH FROM 
|   CURDATE()) 
|   AND 
|   DAYOFMONTH(`birthday`) >= DAYOFMONTH(CURDATE()) 
|   AND 
|   DAYOFMONTH(`birthday`) <= (DAYOFMONTH(CURDATE()) +  15) 
|   ) 
|
|   OR (
|   EXTRACT(MONTH FROM `birthday`) = EXTRACT(MONTH FROM 
|   ADDDATE(CURDATE(), INTERVAL 15 DAY))  
|   AND 
|   DAYOFMONTH(`birthday`) <= DAYOFMONTH(ADDDATE(CURDATE(), 
|   INTERVAL 15 DAY))
|   )

The logic should be clear from the query itself. Note that in one place I use numerical addition (DAYOFMONTH(CURDATE()) + 15) while lower down I use the ADDDATE function. This distinction is important.

Would be happy if someone could refine the above method.

- Noel Athaide.

PS: Put this into a script and crontab it...and you have a simple Birthday reminder :-)

Posted by on January 12, 2006

the birthday-reminder doesn't work the way it should be. I found the bug and fixed it. this is a working example:

SELECT user_birthdate,user_name,user_id , EXTRACT(MONTH FROM `user_birthdate` ) month, EXTRACT(DAY FROM `user_birthdate` ) day
FROM ".$db_prefix."users
WHERE
(
EXTRACT(MONTH FROM `user_birthdate` ) = EXTRACT(MONTH FROM CURDATE())
AND
DAYOFMONTH(`user_birthdate`) > DAYOFMONTH(CURDATE())
AND
DAYOFMONTH(`user_birthdate`) <= (DAYOFMONTH(CURDATE()) + 15)
)
OR
(
EXTRACT(MONTH FROM ADDDATE(CURDATE(), INTERVAL 15 DAY))<>EXTRACT(MONTH FROM CURDATE())
AND
EXTRACT(MONTH FROM `user_birthdate`) = EXTRACT(MONTH FROM ADDDATE(CURDATE(), INTERVAL 15 DAY))
AND
DAYOFMONTH(`user_birthdate`) <= DAYOFMONTH(ADDDATE(CURDATE(), INTERVAL 15 DAY))
)
ORDER BY month, day, user_id ASC

sorry for the strange name, but this is the way my table are named...

hope you like it

Posted by Stijn Tas on January 23, 2006

I'm using this query for a birthday-reminder:

SELECT `geb_Geboorte`
FROM `gebruikers`
WHERE
DAYOFYEAR( curdate( ) ) <= dayofyear( `geb_Geboorte` )
AND
DAYOFYEAR( curdate( ) ) +15 >= dayofyear( `geb_Geboorte` );

I change the year of birthday to the current year.
Sorry for the dutch tablenames.

Posted by John L. on January 25, 2006

It took me a bit of time to find how to select data based on time periods (such as for quarterly or yearly reports). You can use group by month(DateTypeColumn).

example- to find periodic totals:
SELECT [Year|Quarter|Month|Day](date) as Period,shipcountry,shipstate,shipcity,sum(products),sum(shipping),sum(tax)
FROM products NATURAL JOIN shipping NATURAL JOIN tax
GROUP BY Period,shipcountry,shipstate,shipcity

more here-
http://dev.mysql.com/doc/refman/5.0/en/date-and-time-functions.html

I suppose you could alter the start of quarterly periods by doing some arithmetic on the (date), but you might have to do some conversions.

Posted by on March 6, 2006

Time arithmetic using CURTIME() is quite willing to type everything into integers rather than adding and subtracting seconds. For example, where log_time is a TIME column;

SELECT log_time AS Time FROM call_log
WHERE log_time >= (CURTIME( ) - 60 );

will fetch all results from the last 60 seconds. However,

SELECT log_time AS Time FROM call_log
WHERE log_time >= (CURTIME( ) - 900 );

will fetch all results from the last 9 minutes. 900 is interpreted, not as 900 seconds (15 minutes), but as 9:00. An hour is 10000 (1:00:00), not 3600 (36:00).

If you want to add seconds, use something like the following (for the last hour);

SELECT log_time AS Time FROM call_log
WHERE log_time >= (CURTIME( ) - SEC_TO_TIME(3600) );

Posted by Issac Goldstand on March 9, 2006

If you have a column of date values and you want to compare the day portion of them with today's date, taking in mind shorter months which might not contain all the dates in your set (example, billing systems or anything else which needs to run on each record or recordset on a given day of the month), you can try one of these (replacing '2002-04-30' with the date field you're comparing):

SELECT DATE_FORMAT(CURDATE()-INTERVAL 1 MONTH, CONCAT('%Y-%m-',DAY('2002-04-30')))+INTERVAL 1 MONTH;

This tends to "round down" on missing days - for example for dates ending in 30, this will translate to feb 28 (in february).

Posted by Marko Kruustük on April 5, 2006

In reply to "David Berry on September 17 2004 9:08pm"

Problem: To find week start and end date with user specified start of the week day and user specified date for which the week is to be found.

David's solution does not work with user specified week start and end. It only works with normal week which is 1 and 7 as start and end correspondingly.

As I needed different starting day for week than Sunday or Monday for timesheet calculations, I had to come up with working solution:

...

date_sub(t.date, interval if(dayofweek(t.date)-$weekStartingDay >= 0, dayofweek(t.date)-$weekStartingDay, dayofweek(t.date)-$weekStartingDay+7) day) week_start

...

date_sub(t.date, interval if(dayofweek(t.date)-$weekStartingDay >= 0, dayofweek(t.date)-$weekStartingDay, dayofweek(t.date)-$weekStartingDay+7) - 6 day) week_end

...

This solution works fine for me, at least at the moment till I find some bug in it :)

Posted by Bryce Boe on April 14, 2006

Use this to find the date of the last Friday. Please let me know if there is a more efficient way of doing this.

select if(DATE_FORMAT(curdate(),'%w')>4,date_sub(curdate(),INTERVAL DATE_FORMAT(curdate(),'%w')-5 DAY),date_sub(curdate(),INTERVAL DATE_FORMAT(curdate(),'%w')+2 DAY))

Posted by Horst Schirmeier on April 17, 2006

Just another example on how to figure out how many days are until some birthdate (in order to do a range query, or get the "next" birthday):

SELECT name, birthday,
IF(DAYOFYEAR(birthday) >= DAYOFYEAR(NOW()),
DAYOFYEAR(birthday) - DAYOFYEAR(NOW()),
DAYOFYEAR(birthday) - DAYOFYEAR(NOW()) +
DAYOFYEAR(CONCAT(YEAR(NOW()),'-12-31')))
AS distance
FROM birthdates;

The + DAYOFYEAR(CONCAT(YEAR(NOW()),'-12-31')) (which is 366 or 365, depending on whether we're in a leap year or not) takes care of the New Year's Eve wrap around.

You could add WHERE distance <= 10 or ORDER BY distance ASC LIMIT 1 at the end of the query, for example.

Posted by Frederick Ducharme on May 9, 2006

A simple way to get the number of month between 2 date :

SELECT PERIOD_DIFF(EXTRACT(YEAR_MONTH FROM mydate1), EXTRACT(YEAR_MONTH FROM mydate2)) AS month_interval
FROM ....

Posted by Dmitry Dimov on June 5, 2006

Here's what I used to get a summary of some value by day of the week:

select date_format(date, "%W") AS `Day of the week`, sum(cost)
from daily_cost
group by `Day of the week`
order by date_format(date, "%w")

Output:

+-----------------+-----------+
| Day of the week | sum(cost) |
+-----------------+-----------+
| Sunday          | 271.53    |
| Monday          | 310.95    |
| Tuesday         | 323.6     |
| Wednesday       | 312.45    |
| Thursday        | 301.76    |
| Friday          | 294.76    |
| Saturday        | 255.83    |
+-----------------+-----------+

To order results starting with Monday, change the "order by" expression to

order by (date_format(date, "%w") - 7) % 7

Posted by Jens Hopp on June 6, 2006

LAST_DAY() with MySQL 3.23

Need to show the 1st day of the next month? - and were happy to find LAST_DAY() and just thought about adding one single day to its result? - and then discovered that you need MySQL 4+ for that?

Use this ugly chain of functions to show the 1st day of the next month - in MySQL 3.23:

FROM_DAYS(TO_DAYS(CONCAT(SUBSTRING(PERIOD_ADD(DATE_FORMAT(mydate,"%y%m" ),1),3,4),"01")))

You could subtract one day to simulate LAST_DAY() at all.

Posted by Richard Wolterink on July 10, 2006

I made a Stored Function which can covert an ISO 8601 (2006-07-05T13:30:00+02:00) date to a UNIX TIMESTAMP of the corresponding UTC or GMT datetime, so you can compare timestamps from different timezones with eachother. Hope this can help someone.

CREATE FUNCTION ISO8601TOUNIXTIMESTAMP (iso varchar(25))
RETURNS INTEGER(15)
DETERMINISTIC
BEGIN
DECLARE CONVTIME INTEGER(11);
SET CONVTIME = (SUBSTRING(iso,21,2) * 60) + SUBSTRING(iso,24,2);
IF SUBSTRING(iso,20,1) = '+' THEN
SET CONVTIME = 0 - CONVTIME;
END IF;
RETURN UNIX_TIMESTAMP(DATE_ADD(STR_TO_DATE(CONCAT(SUBSTRING(iso,1,10),' ',SUBSTRING(iso,12,8)),'%Y-%m-%d %H:%i:%s'), INTERVAL CONVTIME MINUTE));
END

Posted by Azizur Rahman on July 12, 2006

To get the first day of the current month:

SELECT ((PERIOD_ADD(EXTRACT(YEAR_MONTH FROM CURDATE()),0)*100)+1) as FirstDayOfTheMonth;

This will give you the first day of the month.

mysql> SELECT ((PERIOD_ADD(EXTRACT(YEAR_MONTH FROM CURDATE()),0)*100)+1) as FirstDayOfTheMonth;

+--------------------+
| FirstDayOfTheMonth |
+--------------------+
|           20060701 |
+--------------------+

1 row in set

To get the last day of the current month:

SELECT (SUBDATE(ADDDATE(CURDATE(),INTERVAL 1 MONTH),INTERVAL DAYOFMONTH(CURDATE())DAY)) AS LastDayOfTheMonth;

This will give you the first day of the month.

mysql> SELECT (SUBDATE(ADDDATE(CURDATE(),INTERVAL 1 MONTH),INTERVAL DAYOFMONTH(CURDATE())DAY)) AS LastDayOfTheMonth;

+-------------------+
| LastDayOfTheMonth |
+-------------------+
| 2006-07-31        |
+-------------------+

1 row in set

Hope this helps!

Posted by Jordan Gray on August 1, 2006

This function will return the difference between two dates as a string, in the format "Y year[s], M month[s], D day[s]" (pluralisation as appropriate):

|CREATE FUNCTION getDateDifferenceString(date1 DATE, date2 DATE) RETURNS VARCHAR(30)
|  RETURN CONCAT(
|    /* Years between */
|    @years := TIMESTAMPDIFF(YEAR, date1, date2),
|    IF (@years = 1, ' year, ', ' years, '),
|    /* Months between */
|    @months := TIMESTAMPDIFF(MONTH, DATE_ADD(date1, INTERVAL @years YEAR), date2),
|    IF (@months = 1, ' month, ', ' months, '),
|    /* Days between */
|    @days := TIMESTAMPDIFF(DAY, DATE_ADD(date1, INTERVAL @years * 12 + @months MONTH), date2),
|    IF (@days = 1, ' day', ' days')
|  )
|;

It took a while to work this one out, so I hope this might save someone else the bother.

Posted by Daevid Vincent on August 4, 2006

I'm not sure why Horst Schirmeier did that very complex birthdate equation. Seems to me you could just do:

SET @DOYNOW = DAYOFYEAR(CURDATE());

SELECT (DAYOFYEAR(birthdate) - @DOYNOW) AS birthdays, birthdate, @DOYNOW, CURDATE()
FROM users
WHERE birthdate IS NOT NULL;

then if birthdays == 0, it's that persons birthday, otherwise you know if the birthday is in the future by how many days, or if you missed it and how many beers you owe them...

(although the missed/negative days seems to be off)

+-----------+------------+---------+------------+
| birthdays | birthdate  | @DOYNOW | CURDATE()  |
+-----------+------------+---------+------------+
|        83 | 1969-10-26 | 216     | 2006-08-04 | 
|         3 | 1981-08-07 | 216     | 2006-08-04 | 
|        -1 | 1972-08-02 | 216     | 2006-08-04 | 
|         0 | 1946-08-04 | 216     | 2006-08-04 | 
|      -151 | 1976-03-05 | 216     | 2006-08-04 | 
+-----------+------------+---------+------------+

Shouldn't that -1 be -2 ?
Am I missing something obvious?

If I do "SELECT DATEDIFF('2006-08-01', CURDATE());" I get -2 as I expect.

So, I guess the real solution is to use this:

SET @YEAR = CONCAT(EXTRACT(YEAR FROM CURDATE()),'-');

SELECT DATEDIFF(CONCAT(@YEAR, DATE_FORMAT(birthdate, '%m-%d')), CURDATE()) AS birthdays, birthdate, CURDATE()
FROM users
WHERE birthdate IS NOT NULL;

+-----------+------------+------------+
| birthdays | birthdate  | CURDATE()  |
+-----------+------------+------------+
|        83 | 1969-10-26 | 2006-08-04 | 
|         3 | 1981-08-07 | 2006-08-04 | 
|        -2 | 1972-08-02 | 2006-08-04 | 
|         0 | 1946-08-04 | 2006-08-04 | 
|      -152 | 1976-03-05 | 2006-08-04 | 
+-----------+------------+------------+

By the way, if you're using PHP or some other scripting language, you can get rid of the @YEAR stuff and just do:

DATEDIFF(DATE_FORMAT(birthdate, '".date('Y')."-%m-%d'), CURDATE()) AS birthdays

Posted by Arturas D. on August 18, 2006

Keyphrases: Birthday reminder

This is another query for the birthday remainder :

|  SELECT * FROM `users`
|  WHERE 
|  ( 
|    DAYOFYEAR( NOW() ) > DAYOFYEAR( DATE_SUB(birthdate,INTERVAL 7 DAY) ) 
|    AND
|    DAYOFYEAR( NOW() ) <= DAYOFYEAR( DATE_SUB(birthdate,INTERVAL 7 DAY) )+7 
|  )
|  OR
|  ( 
|    DAYOFYEAR( NOW() ) > DAYOFYEAR( birthdate )-7 
|    AND 
|    DAYOFYEAR( NOW() ) <= DAYOFYEAR( birthdate ) 
|  );

Posted by jeremy levine on August 22, 2006

Get the first day and/or last day of the current year.

This is the first day of the year ( simple )
SELECT MAKEDATE( EXTRACT(YEAR FROM CURDATE()),1);

This is the last day ( not you can not just replace the 1 with a 365 , some years you need a 366)

SELECT STR_TO_DATE(CONCAT(12,31,EXTRACT(YEAR FROM CURDATE())), '%m%d%Y') ;

Posted by Dave Green on September 14, 2006

SERIAL DATES
------------

to convert dates stored as a double (Dateserial as used by microsoft etc i.e. 38883.8941421412. The whole number is the number of days since either 31/12/1899 or 01/01/1900, the fraction being the proportion of 1 day) into a dd/mm/yyyy hh:mm format:

note - MySQL requires the date taken from 31/12/1899, and even then the addition of number of days is still out by 1 because MySQL like Excel and other programs incorrectly assumes that the year 1900 was a leap year, when it wasn't for some reason.

The SQL to get the correct date is:-
ADDDATE(ADDDATE('1899-12-31 00:00',<serial date>), INTERVAL -1 DAY)

The fraction of the time can be multiplied by the number of seconds in a day (84,600) and then added to the date as a number of seconds to get the time as well, so for a datetime the SQL is:-
ADDDATE(ADDDATE(ADDDATE('1899-12-31 00:00',<serial date>), INTERVAL -1 DAY), INTERVAL (MOD(<serial date>,1) * 86400) SECOND)

Sorry is this is a bit obvious, it just took me a while to find all this out. Hope it helps.

Posted by Erel Segal on November 1, 2006

Note that the order of arguments in TIMEDIFF is opposite than in TIMESTAMPDIFF, so:

TIMESTAMPDIFF(SECOND,expr1,expr2) = TIME_TO_SEC(TIMEDIFF(expr2,expr1))

Posted by Amit Kondhare on November 9, 2006

No ready made function is provided for validate date

This function work
(you can take what ever size you want in varchar(1-1024) )

CREATE FUNCTION IsDate (sIn varchar(1024)) RETURNS INT
BEGIN
declare tp int;

if length(date(sIn)) is not null then
set tp = 0;
else
set tp = 1;
end if;
RETURN tp;
END
If you find any bug for this please post it here as this is not complete soluction as date respond are not known
I will try to solve this

Posted by Ron A. on November 14, 2006

Get date for first day of current week if first day of week is monday (SWEDEN, FRANCE, etc):

MONDAY
select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) -0 DAY)

TUESDAY
select date_sub(curdate(),INTERVAL WEEKDAY(curdate()) -1 DAY)

AND SO ON...

Posted by Antonio Angelo on January 17, 2007

The ISO 8601 week number is defined as the number of the week containing the first Thursday.
With this definition, the ISO week number corresponds to WEEK(date, 3) .

The following returns 1 for the week between 2003-12-29 and 2004-01-04:

| SELECT 
| WEEK('2003-12-29', 3),
| WEEK('2004-01-04', 3)

Posted by Martin Minka on January 25, 2007

I created this function to calculate "working day" difference of two dates. If you have table with list of holidays you may uncomment part in this function to exclude days of holidays also.

DELIMITER $$

DROP FUNCTION IF EXISTS `workdaydiff`$$

CREATE DEFINER=`root`@`%` FUNCTION `workdaydiff`(b date, a date) RETURNS int(11)
DETERMINISTIC
COMMENT 'working day difference for 2 dates'
BEGIN
DECLARE freedays int;
SET freedays = 0;

SET @x = DATEDIFF(b, a);
IF @x<0 THEN
SET @m = a;
SET a = b;
SET b = @m;
SET @m = -1;
ELSE
SET @m = 1;
END IF;
SET @x = abs(@x) + 1;
/* days in first week */
SET @w1 = WEEKDAY(a)+1;
SET @wx1 = 8-@w1;
IF @w1>5 THEN
SET @w1 = 0;
ELSE
SET @w1 = 6-@w1;
END IF;
/* days in last week */
SET @wx2 = WEEKDAY(b)+1;
SET @w2 = @wx2;
IF @w2>5 THEN
SET @w2 = 5;
END IF;
/* summary */
SET @weeks = (@x-@wx1-@wx2)/7;
SET @noweekends = (@weeks*5)+@w1+@w2;
/* Uncoment this if you want exclude also hollidays
SELECT count(*) INTO freedays FROM holliday WHERE d_day BETWEEN a AND b AND WEEKDAY(d_day)<5;
*/
SET @result = @noweekends-freedays;
RETURN @result*@m;
END$$

DELIMITER ;

Posted by Jemma Hussein on January 31, 2007

If you want to select the time difference between two datetime columns and the fields may contain datetimes that are on different days, you can use the following if statement:

SELECT IF(TIME_TO_SEC(last_date)>=TIME_TO_SEC(first_date),
TIME_TO_SEC(last_date)-TIME_TO_SEC(first_date),
86400+(TIME_TO_SEC(last_date)-TIME_TO_SEC(first_date)))
FROM table;

This will return the time between the last_date and the first date, taking into account the values where first_date and last_date are on different days.

Posted by Will Jaspers on May 2, 2007

NOTE: DateFormat cannot be used to format a TimeDiff calculation.

Example:
SELECT DATE_FORMAT(TIMEDIFF(`appointment_start`,`appointment_end`),'%H:%i:%s')) AS duration FROM appointments;

Correct Syntax:
SELECT TIMEDIFF(`appointment_start`,`appointment_end`) AS duration FROM appointments;

(Tested on MySQL 4.1.20)

Posted by on May 31, 2007

My pick on birthdays remainders :

select date_format( date, "%d/%m" ), DAYOFYEAR( CURDATE( ) ), DAYOFYEAR( date )
from table
where DAYOFYEAR( date ) between DAYOFYEAR( CURDATE( ) ) - 15 and DAYOFYEAR( CURDATE( ) ) + 15
order by date_format( date, "%d/%m/%Y" )

Gabriel Reguly http://ppgr.com.br

Posted by Eject Disc on June 11, 2007

As mentioned above STR_TO_DATE() is available as of MySQL 4.1.1.

This function can be useful if you are grouping rows by Week of Year and then want to produce a table with "Week Commencing" as the points on your X-axis.

So what do you do if you're codeshop is using pre-4.1?

Here's what I did. I have a table of events happening on a datetime. I wanted an event count by week with the date of the start of the week, assuming the week starts Monday.

I have exploited the group by function to extract the minimum datetime value which in my case is guaranteed to be at least once daily.

This will not work if your data is not being injected daily!

select
count(*) as 'count',
date_format(min(added_on), '%Y-%M-%d') as 'week commencing',
date_format(added_on, '%Y%u') as 'week'
from
system
where
added_on >= '2007-05-16'
group by
week
order by 3 desc;

+-------+-----------------+--------+
| count | week commencing | week   |
+-------+-----------------+--------+
|    88 | 2007-June-04    | 200723 |
|   276 | 2007-May-28     | 200722 |
|   275 | 2007-May-21     | 200721 |
|   160 | 2007-May-16     | 200720 |
+-------+-----------------+--------+

Hope thats useful for someone !

Imran Chaudhry

Posted by Andrew Holloway on August 8, 2007

Due to a bug in mysql versions prior to 5.0.36, there is a problem when performing multiple SEC_TO_TIME conversions and there are intermediate null values. It will turn the results after the first null into null values.

For example: if you have a table (date_diff) as follows:

|id    | time1   | time2     |
+------+---------+-----------+
|1     | 9:30:05 |     (null)|
|2     | 10:05:07|   10:05:17|
|3     | 11:00:03|   11:01:00|
|4     | 12:05:11|     (null)|

and you run a query:

select sec_to_time(time_to_sec(time1) - time_to_sec(time2)) as diff from date_diff;

You will see results as so:

|  diff  |
+--------+
|00:00:00|
|  (null)|
|  (null)|
|  (null)|

And a query excluding id 1 will result in:

|  diff  |
+--------+
|00:00:10|
|00:00:57|
|00:00:00|

A workaround would be to use a case statement:

select case when isnull(time_to_sec(time1) - time_to_sec(time2)) then null else sec_to_time(time_to_sec(time1) - time_to_sec(time2)) end as diff from date_diff;

Or, upgrade to a mysql version including this bug fix (#25643).

Posted by Marcel Brouillet on August 16, 2007

To display the date of the monday preceding a given day, Bryan Donovan suggested the following:
> SELECT DISTINCT(STR_TO_DATE(CONCAT(YEARWEEK(starttime),'1'),'%x%v%w'))
> FROM test_events;

In fact, you need to be consistent in the type of weeks you use. The above would tell you that the Monday July 16 2007 is part of the week starting... Monday July 9 2007 !
This comes from week definition ambiguities (see WEEK() above). To prevent this, specify the mode on YEARWEEK to be Monday-based : pay attention to the extra parameter to the function YEARWEEK) below

+--------------------------------+
| DATE_FORMAT('2007-07-16',"%W") |
+--------------------------------+
| Monday                         | 
+--------------------------------+
+----------------------------------------------------------+
| STR_TO_DATE(CONCAT(YEARWEEK('2007-07-16'),'1'),'%x%v%w') |
+----------------------------------------------------------+
| 2007-07-09                                               | 
+----------------------------------------------------------+
+------------------------------------------------------------+
| STR_TO_DATE(CONCAT(YEARWEEK('2007-07-16',1),'1'),'%x%v%w') |
+------------------------------------------------------------+
| 2007-07-16                                                 | 
+------------------------------------------------------------+

One would expect that default_week_format has the same effect on WEEKDAY() than it has on WEEK() and that setting this variable to 1 or 3 would suffice. No, as of Mysql 5.0.26 it seems to have no effect:

SET default_week_format=1;
SELECT STR_TO_DATE(CONCAT(YEARWEEK('2007-07-16'),'1'),'%x%v%w')

+----------------------------------------------------------+
| 2007-07-09                                               | 
+----------------------------------------------------------+

Posted by Dave Holden on September 6, 2007

ANNIVERSARIES ARE TRICKY!
-------------------------

For versions of MySQL previous to 4.1 it is quite difficult to determine if a date field's anniversary date falls within a specified date range. Day-of-year calculations fail because of leap years and the possibility that the date range you have specified spans a year boundary. Here is what I have come up with. Hopefully it can save someone the headache and Google Fever I had to go through to come up with it.

** SOME SELECT STATEMENT ...**
WHERE
((month(Date) BETWEEN month('[MyStartDate]') AND month('[MyEndDate]')
AND
month('[MyStartDate]') <= month('[MyEndDate]')
AND
(dayofmonth(Date) >= dayofmonth('[MyStartDate]') AND month(Date)=month('[MyStartDate]')
OR
dayofmonth(Date) <= dayofmonth('[MyEndDate]') AND month(Date)=month('[MyEndDate]')
OR
month(date) > month('[MyStartDate]') AND month(date) < month('[MyEndDate]')))

OR

(
month('[MyStartDate]') > month('[MyEndDate]')
AND
(dayofmonth(Date) >= dayofmonth('[MyStartDate]') AND month(Date)=month('[MyStartDate]')
OR
dayofmonth(Date) <= dayofmonth('[MyEndDate]') AND month(Date)=month('[MyEndDate]')
OR
month(Date) > month('[MyStartDate]')
OR month(Date) < month('[MyEndDate]')
)))

Posted by Darren Edwards on September 6, 2007

I was looking for a solution where I could return the number of days, hours, Minutes and seconds between two entries in a table.
DATE_DIFF is not running on my mysql server as my provider uses mysql version 4.0.25
Solution was to use to days and std time functions to calculate the difference in one call.
The fields stored in the table(report_table) are
time(00:00:00),
date(0000-00-00) and record(enum) which tells the app the type of log stored. EG start or end of a report.

SELECT
(TO_DAYS( `end`.`date` ) - TO_DAYS( `start`.`date` ))
-
( second( `end`.`time` ) + (minute( `end`.`time` )*60) + (hour( `end`.`time` )*3600)
<
second( `start`.`time` ) + (minute( `start`.`time` )*60) + (hour( `start`.`time` )*3600))
AS `days` ,
SEC_TO_TIME(
(second( `end`.`time` ) + (minute( `end`.`time` )*60) + (hour( `end`.`time` )*3600) )
-
(second( `start`.`time` ) + (minute( `start`.`time` )*60) + (hour( `start`.`time` )*3600) )
) AS `hms`,
`start`.`time` as `start`,
`end`.`time` as `end`

FROM `report_table` AS `start` , `report_table` AS `end`
AND `start`.`record` = 'Report Begin'
AND `end`.`record` = 'Report End'
LIMIT 1

If there is no end of report then it will not return a result, as you would expect.

Posted by Robert Jaemmrich on October 12, 2007

Birthday reminder

The next birthday (including today!) is when the person is 1 year older than he/she was yesterday. So I use

mysql> select name,birthday,adddate(birthday,interval timestampdiff(year,adddate(birthday,interval 1 day),current_date)+1 year) as next_bd from person order by next_bd;

+----------+------------+------------+
| name     | birthday   | next_bd    |
+----------+------------+------------+
| FooToday | 1970-10-12 | 2007-10-12 | 
| Bar1     | 1990-12-25 | 2007-12-25 | 
| Bar2     | 2000-01-25 | 2008-01-25 | 
| Foo      | 1980-02-29 | 2008-02-29 | 
+----------+------------+------------+

4 rows in set (0.00 sec)

mysql> select name,birthday,adddate(birthday,interval timestampdiff(year,adddate(birthday,interval 1 day),'2008-10-12')+1 year) as next_bd from person order by next_bd;

+----------+------------+------------+
| name     | birthday   | next_bd    |
+----------+------------+------------+
| FooToday | 1970-10-12 | 2008-10-12 | 
| Bar1     | 1990-12-25 | 2008-12-25 | 
| Bar2     | 2000-01-25 | 2009-01-25 | 
| Foo      | 1980-02-29 | 2009-02-28 | 
+----------+------------+------------+

4 rows in set (0.00 sec)

As you can see, this is also working for leap years.

BTW: Is "2008-02-29" plus 1 year" really "2009-02-28"? ;-)

Posted by Aaron Davidson on December 6, 2007

To test if a date is a valid date:

SET @testdate="2007-02-29";
SELECT IF(@testdate=DATE_ADD(DATE_ADD(@testdate,INTERVAL 1 DAY),INTERVAL -1 DAY),TRUE,FALSE);

Returns 0 (false)

SET @testdate="2008-02-29";
SELECT IF(@testdate=DATE_ADD(DATE_ADD(@testdate,INTERVAL 1 DAY),INTERVAL -1 DAY),TRUE,FALSE);

Returns 1 (true)

Posted by Mohamed Infiyaz Zaffer Khalid on December 12, 2007

Finding a date before a given number of days

Often, for certain applications, we need to subtract some days from a given date to find another date. For example, in a library, we need to go 21 days behind from the current date and list the books that were taken before that date. This would be the overdue list.

Here is a simple SQL statement. This type of use is practically essential to most apps.

SELECT SUBDATE( '2007-12-12', INTERVAL 3 DAY ) ;

The line above will give the answer 2007-12-9. To explain it further, the function SUBDATE returns a date after subtracting a specified duration. In our example, the duration is 3 days. To indicate that we are dealing with DAYS, we use the term INTERVAL. So the function above can be explained as “what is the date, three days before today?”

Now if you want to find the date 20 days before TODAY or the current system date, this is what you should do:

SELECT SUBDATE( CURRENT_DATE, INTERVAL 20 DAY )

In the statement above, we are using one of the MySQL constants that hold the current date on the server. We count 20 days back and get the answer as a result.

Happy coding.

Khalid (itsols)

Posted by Marcus Matos on January 8, 2008

Important: It should be known that MySQL >= 5.0.42 silently changes the behavior of comparing a DATE column to NOW().

See: http://bugs.mysql.com/bug.php?id=28929

This breaks many things since now queries using WHERE datecol = NOW() will return NULL where previously it would return results.

Use CURDATE() instead. I'm having to go back through years of code to fix this.

Posted by Tomasz Kopec on January 17, 2008

refering to the document section telling about intervals in date_add / date_sub functions describing example :
SELECT DATE_ADD('1999-01-01', INTERVAL 6/4 HOUR_MINUTE);
One can avoid falling into trap simply enclosing interval 6/4 into quotation marks so the query will be look like this:
SELECT DATE_ADD('1999-01-01', INTERVAL '6/4' HOUR_MINUTE);
This case the interval will be considered as regular string and no calculation will be performed before passing as argument

Posted by Mohamed Mahir on January 23, 2008

Earlier I used timediff in where clause worked perfectly but don't know why it is not working now especially after cpu usage exceeds in *in two different shared hosting*

query like

select * from table where timediff(sysdate(),datetimecolumn)<25

this gets rows of last 24 hours.

Posted by Phill Pafford on May 15, 2008

IF you need to run a monthly report from the 1st of each month with the previous month date, you could use the case statement below.

SELECT CASE
WHEN MONTH(CURDATE()) = 01
THEN SUBDATE(CURDATE(), INTERVAL 31 DAY) /* Dec */
WHEN MONTH(CURDATE()) = 02
THEN SUBDATE(CURDATE(), INTERVAL 31 DAY) /* Jan */
WHEN MONTH(CURDATE()) = 03 AND (YEAR(CURDATE())%4 = 0)
THEN SUBDATE(CURDATE(), INTERVAL 29 DAY) /* Feb Leap Year */
WHEN MONTH(CURDATE()) = 03 AND (YEAR(CURDATE())%4 != 0)
THEN SUBDATE(CURDATE(), INTERVAL 28 DAY) /* Feb */
WHEN MONTH(CURDATE()) = 04
THEN SUBDATE(CURDATE(), INTERVAL 31 DAY) /* Mar */
WHEN MONTH(CURDATE()) = 05
THEN SUBDATE(CURDATE(), INTERVAL 30 DAY) /* Apr */
WHEN MONTH(CURDATE()) = 06
THEN SUBDATE(CURDATE(), INTERVAL 31 DAY) /* May */
WHEN MONTH(CURDATE()) = 07
THEN SUBDATE(CURDATE(), INTERVAL 30 DAY) /* Jun */
WHEN MONTH(CURDATE()) = 08
THEN SUBDATE(CURDATE(), INTERVAL 31 DAY) /* Jul */
WHEN MONTH(CURDATE()) = 09
THEN SUBDATE(CURDATE(), INTERVAL 31 DAY) /* Aug */
WHEN MONTH(CURDATE()) = 10
THEN SUBDATE(CURDATE(), INTERVAL 30 DAY) /* Sep */
WHEN MONTH(CURDATE()) = 11
THEN SUBDATE(CURDATE(), INTERVAL 31 DAY) /* Oct */
WHEN MONTH(CURDATE()) = 12
THEN SUBDATE(CURDATE(), INTERVAL 30 DAY) /* Nov */
ELSE SUBDATE(CURDATE(), INTERVAL 30 DAY) /* Defaults to 30 days */
END

Should return 'YYYY-MM-DD' from day and interval you run it on.

Example:

if the date is Jan 1st 2008 the case will return '2007-12-01'

Added this to get the 1st of the month when you run from any day of the month

SELECT CASE
WHEN MONTH(CURDATE()) = 01
THEN SUBDATE(CURDATE(), INTERVAL (31 - (DAYOFMONTH(CURDATE()) +1 )) DAY) /* Dec */
WHEN MONTH(CURDATE()) = 02
THEN SUBDATE(CURDATE(), INTERVAL (31 - (DAYOFMONTH(CURDATE()) +1 )) DAY) /* Jan */
WHEN MONTH(CURDATE()) = 03 AND (YEAR(CURDATE())%4 = 0)
THEN SUBDATE(CURDATE(), INTERVAL (29 - (DAYOFMONTH(CURDATE()) +1 )) DAY) /* Feb Leap Year */
WHEN MONTH(CURDATE()) = 03 AND (YEAR(CURDATE())%4 != 0)
THEN SUBDATE(CURDATE(), INTERVAL (28 - (DAYOFMONTH(CURDATE()) +1 )) DAY) /* Feb */
WHEN MONTH(CURDATE()) = 04
THEN SUBDATE(CURDATE(), INTERVAL (31 - (DAYOFMONTH(CURDATE()) +1 )) DAY) /* Mar */
WHEN MONTH(CURDATE()) = 05
THEN SUBDATE(CURDATE(), INTERVAL (30 - (DAYOFMONTH(CURDATE()) +1 )) DAY) /* Apr */
WHEN MONTH(CURDATE()) = 06
THEN SUBDATE(CURDATE(), INTERVAL (31 - (DAYOFMONTH(CURDATE()) +1 )) DAY) /* May */
WHEN MONTH(CURDATE()) = 07
THEN SUBDATE(CURDATE(), INTERVAL (30 - (DAYOFMONTH(CURDATE()) +1 )) DAY) /* Jun */
WHEN MONTH(CURDATE()) = 08
THEN SUBDATE(CURDATE(), INTERVAL (31 - (DAYOFMONTH(CURDATE()) +1 )) DAY) /* Jul */
WHEN MONTH(CURDATE()) = 09
THEN SUBDATE(CURDATE(), INTERVAL (31 - (DAYOFMONTH(CURDATE()) +1 )) DAY) /* Aug */
WHEN MONTH(CURDATE()) = 10
THEN SUBDATE(CURDATE(), INTERVAL (30 - (DAYOFMONTH(CURDATE()) +1 )) DAY) /* Sep */
WHEN MONTH(CURDATE()) = 11
THEN SUBDATE(CURDATE(), INTERVAL (31 - (DAYOFMONTH(CURDATE()) +1 )) DAY) /* Oct */
WHEN MONTH(CURDATE()) = 12
THEN SUBDATE(CURDATE(), INTERVAL (30 - (DAYOFMONTH(CURDATE()) +1 )) DAY) /* Nov */
ELSE SUBDATE(CURDATE(), INTERVAL (30 - (DAYOFMONTH(CURDATE()) +1 )) DAY) /* Defaults to 30 days */
END

Posted by Thomas Schäfer on March 4, 2008

Titel: Urlaubstage im laufenden Kalenderjahr anhand eines Arbeitstagemodells berechnen

Variablen $workable[First-Seventh] bool 1=Arbeitstag, 0=Kein Arbeitstag

$query ="
SELECT
SUM(effectiveworkdays(vrs.confirmed_from, vrs.confirmed_to, $workableFirst, $workableSecond, $workableThird, $workableFourth, $workableFifth, $workableSixth, $workableSeventh)) AS sum
FROM app_vacation_responses vrs
LEFT JOIN app_vacation_requests vrq ON vrs.request_id = vrq.vacation_id
WHERE vrq.requested_by = ". $employee_id ."
AND vrs.confirmed_from >= '". date('Y') ."-01-01'
AND vrs.confirmed_to <= '". date('Y') ."-12-31'
AND vrs.state = 1
group by vrq.requested_by
";

DELIMITER $$

DROP FUNCTION IF EXISTS `effectiveworkdays`$$

CREATE DEFINER=`myUserName`@`myHost` FUNCTION `effectiveworkdays`(STARTDATE date, ENDDATE date, WORKABLE1 integer, WORKABLE2 integer, WORKABLE3 integer, WORKABLE4 integer, WORKABLE5 integer, WORKABLE6 integer, WORKABLE7 integer) RETURNS int(11)
DETERMINISTIC
COMMENT 'effective working day for 2 dates'
BEGIN
DECLARE DAYCOUNT int;
DECLARE HOLIDAYCOUNT, HOLIDAYS int;
DECLARE STARTDAYS int;
DECLARE ENDDAYS int;

SET DAYCOUNT = 0;
SET HOLIDAYCOUNT = 0;
SET HOLIDAYS = 0;
SET STARTDAYS = TO_DAYS(STARTDATE) - 1 ;
SET ENDDAYS = TO_DAYS(ENDDATE);

IF (STARTDAYS <= ENDDAYS) THEN

WHILE (STARTDAYS <= ENDDAYS) DO
SET HOLIDAYCOUNT = 0;
IF(WORKABLE1=1 AND WEEKDAY(FROM_DAYS(STARTDAYS))=0) THEN
SET DAYCOUNT = DAYCOUNT + 1;
SELECT count(*) INTO HOLIDAYCOUNT FROM prop_holidays WHERE d_date = FROM_DAYS(STARTDAYS);
END IF;
IF(WORKABLE2=1 AND WEEKDAY(FROM_DAYS(STARTDAYS))=1) THEN
SET DAYCOUNT = DAYCOUNT + 1;
SELECT count(*) INTO HOLIDAYCOUNT FROM prop_holidays WHERE d_date = FROM_DAYS(STARTDAYS);
END IF;
IF(WORKABLE3=1 AND WEEKDAY(FROM_DAYS(STARTDAYS))=2) THEN
SET DAYCOUNT = DAYCOUNT + 1;
SELECT count(*) INTO HOLIDAYCOUNT FROM prop_holidays WHERE d_date = FROM_DAYS(STARTDAYS);
END IF;
IF(WORKABLE4=1 AND WEEKDAY(FROM_DAYS(STARTDAYS))=3) THEN
SET DAYCOUNT = DAYCOUNT + 1;
SELECT count(*) INTO HOLIDAYCOUNT FROM prop_holidays WHERE d_date = FROM_DAYS(STARTDAYS);
END IF;
IF(WORKABLE5=1 AND WEEKDAY(FROM_DAYS(STARTDAYS))=4) THEN
SET DAYCOUNT = DAYCOUNT + 1;
SELECT count(*) INTO HOLIDAYCOUNT FROM prop_holidays WHERE d_date = FROM_DAYS(STARTDAYS);
END IF;
IF(WORKABLE6=1 AND WEEKDAY(FROM_DAYS(STARTDAYS))=5) THEN
SET DAYCOUNT = DAYCOUNT + 1;
SELECT count(*) INTO HOLIDAYCOUNT FROM prop_holidays WHERE d_date = FROM_DAYS(STARTDAYS);
END IF;
IF(WORKABLE7=1 AND WEEKDAY(FROM_DAYS(STARTDAYS))=6) THEN
SET DAYCOUNT = DAYCOUNT + 1;
SELECT count(*) INTO HOLIDAYCOUNT FROM prop_holidays WHERE d_date = FROM_DAYS(STARTDAYS);
END IF;
SET STARTDAYS = STARTDAYS + 1;
SET HOLIDAYS = HOLIDAYS + HOLIDAYCOUNT;
END WHILE;
END IF;
IF ((STARTDAYS = ENDDAYS) AND (DAYCOUNT = 0)) THEN
SET DAYCOUNT = 1;
END IF;

RETURN DAYCOUNT- HOLIDAYS;
END$$

DELIMITER ;

CREATE TABLE IF NOT EXISTS `prop_holidays` (
`holiday_id` int(11) NOT NULL auto_increment,
`name` varchar(50) NOT NULL,
`d_date` date NOT NULL,
`d_type` varchar(50) default NULL,
`d_subtype` varchar(50) default NULL,
PRIMARY KEY (`holiday_id`)
) ENGINE=MyISAM;

INSERT INTO `prop_holidays` (`holiday_id`, `name`, `d_date`, `d_type`, `d_subtype`) VALUES
(35, 'newYearsDay', '2008-01-01', 'Germany', 'BadenWuerttemberg'),
(36, 'epiphany', '2008-01-06', 'Germany', 'BadenWuerttemberg'),
(37, 'goodFriday', '2008-03-21', 'Germany', 'BadenWuerttemberg'),
(38, 'easterMonday', '2008-03-24', 'Germany', 'BadenWuerttemberg'),
(39, 'dayOfWork', '2008-05-01', 'Germany', 'BadenWuerttemberg'),
(40, 'ascensionDay', '2008-05-12', 'Germany', 'BadenWuerttemberg'),
(41, 'whitMonday', '2008-05-22', 'Germany', 'BadenWuerttemberg'),
(42, 'corpusChristi', '2008-10-03', 'Germany', 'BadenWuerttemberg'),
(43, 'germanUnificationDay', '2008-11-01', 'Germany', 'BadenWuerttemberg'),
(44, 'allSaintsDay', '2008-12-25', 'Germany', 'BadenWuerttemberg'),
(45, 'xmasDay', '2008-12-26', 'Germany', 'BadenWuerttemberg');

EXAMPLE FOR SYMFONY USERS

class VacationResponse extends BaseVacationResponse
{
public function getThisYearsLeaveDaysPaidByUserSum($employee_id){

$c = new Criteria();
$c->add(EmployeePeer::EMPLOYEE_ID, $this->getRequestParameter("id"));
$tmp = EmployeePeer::doSelect($c);
$employee = $tmp[0];

$schedule = $employee->getEmploymentContract()->getWorkSchedule();

$workableFirst = $schedule->getWorkableFirst() ==1?1:0;
$workableSecond = $schedule->getWorkableSecond() ==1?1:0;
$workableThird = $schedule->getWorkableThird() ==1?1:0;
$workableFourth = $schedule->getWorkableFourth() ==1?1:0;
$workableFifth = $schedule->getWorkableFifth() ==1?1:0;
$workableSixth = $schedule->getWorkableSixth() ==1?1:0;
$workableSeventh = $schedule->getWorkableSeventh()==1?1:0;

$query ="
SELECT
sum(effectiveworkdays2(vrs.confirmed_from, vrs.confirmed_to, $workableFirst, $workableSecond, $workableThird, $workableFourth, $workableFifth, $workableSixth, $workableSeventh)) AS sum
FROM app_vacation_responses vrs
LEFT JOIN app_vacation_requests vrq ON vrs.request_id = vrq.vacation_id
WHERE vrq.requested_by = ". $employee_id ."
AND vrs.confirmed_from >= '". date('Y') ."-01-01'
AND vrs.confirmed_to <= '". date('Y') ."-12-31'
AND vrs.state = 1
group by vrq.requested_by
";

$connection = Propel::getConnection();
$statement = $connection->prepareStatement($query);
$resultset = $statement->executeQuery();
$results = null;
foreach($resultset as $result){
if($result["sum"] < 0)
$results = 0;
else
$results = $result["sum"];
}
return $results;
}

}

Posted by Jyotsna Channagiri on March 31, 2008

If you want to find out the difference between date column and integer column you can do like the following:

select DATE_ADD(<col_name_DATE>,INTERVAL -<col_name_INTEGER> UNIT) from <table_name>

col_name_DATE : Should be DATE / DATETIME data type
col_name_INTEGER : Should be INTEGER data Type
UNIT : can be MINUTE,MONTH,....

Posted by M.H. J. on May 5, 2008

For MySQL 4.1 you can use this query to select the month-difference between two dates, which also takes into account the amount of days of the starting month and ending month.

1. The first part is the period_diff function to get a total amount of months between two dates. Then 1 month is subtracted (because of the next two parts).

2. The second part is to calculate the part of the starting-month (results in 1 month for dates starting on the first of the month, like 01-01-2008)

3. The third part is to calculate the part of the ending-month (results in 0 for dates starting on the first of the month, like 01-02-2008)

PERIOD_DIFF(DATE_FORMAT(`end_date`,'%Y%m'),DATE_FORMAT(`start_date`,'%Y%m'))

-1

+ (TO_DAYS(LAST_DAY(`start_date`)) + 1 - TO_DAYS(DATE_FORMAT(`start_date`,'%Y-%m-%d')))/(TO_DAYS(LAST_DAY(`start_date`)) + 1 - to_days(DATE_FORMAT(`start_date`,'%Y-%m-01')))

+ (DAY(`end_date`)-1)/(TO_DAYS(LAST_DAY(`end_date`)) + 1 - TO_DAYS(DATE_FORMAT(`end_date`,'%Y-%m-01')))

Posted by Patrick Bernier on May 10, 2008

A safe and simple way to calculate the age of someone/something:

CREATE FUNCTION age (_d DATETIME) RETURNS INTEGER
COMMENT 'Given birthdate, returns current age'
RETURN YEAR(NOW()) - YEAR(_d) - IF(DATE_FORMAT(_d, '%c%d') > DATE_FORMAT(NOW(), '%c%d'), 1, 0);

Posted by Andy Fugate on May 23, 2008

I work for a publishing company and recently had a request to show the modification date/time for an article as either minutes ago, hours ago, yesterday, or date of last modification depending on how recently the article was last modified. Here's a copy of the case statement I used for this:

CASE
WHEN modified_date between date_sub(now(), INTERVAL 60 minute) and now() THEN concat(minute(TIMEDIFF(now(), modified_date)), ' minutes ago')
WHEN datediff(now(), modified_date) = 1 THEN 'Yesterday'
WHEN modified_date between date_sub(now(), INTERVAL 24 hour) and now() THEN concat(hour(TIMEDIFF(NOW(), modified_date)), ' hours ago')
ELSE date_format(modified_date, '%a, %m/%d/%y')
END

Note that the "yesterday" check occurs before the "hours" check. This is intentional so that hours will only be shown if the modification occurred during the current day.

Hope this is useful for someone else!

Posted by Simon Stefan on July 31, 2008

Here is a selection for a birthday reminder with 2 days before (INTERVAL 2 DAY):

select id, angajat_id, data_nastere from info_angajat
where DATE_ADD(date(concat(YEAR(data_nastere),"-", MONTH(NOW()), "-", DAYOFMONTH(NOW()))), INTERVAL 2 DAY)=data_nastere;

Posted by Chandru N on August 14, 2008

To find the start and end of a month you can use the following queries:
Last day of current month:
SELECT LAST_DAY(now());
Last day of Previous month
SELECT LAST_DAY(now() - interval 1 month );
First day of current month:
SELECT concat(date_format(LAST_DAY(now()),'%Y-%m-'),'01');
First day of previous month:
SELECT concat(date_format(LAST_DAY(now() - interval 1 month),'%Y-%m-'),'01');

Posted by Matias Thayer on October 9, 2008

Hi, here is a MySQL(5) function to validate a date, in format YYYYMMDD (example:"select isDate(20080229)"). This function include "leap year" validation.
I try to simulate "isdate()" function of Sql Server.

DELIMITER $$
CREATE FUNCTION `isDate`(s varchar(100)) RETURNS decimal(8)
BEGIN

/*valida fecha suponiendo que es ingresado como "20081228" (largo 8) */
declare tp int;
declare bisiesto int;

set s=trim(s);
/* realizamos validaciones generales */
if trim(s)=0 and length(trim(s))<>8 then
return 0; /*fecha invalida*/
end if;

if substr(s, 1,4) not between 0 and 9999 then
return 0; /*anno invalido*/
end if;

if substr(s, 5,2) not between 1 and 12 then
return 0; /*mes invalido*/
end if;

/* vemos si es bisiesto el ano */
set bisiesto=0;
if substr(s, 1,4) mod 400 = 0 then set bisiesto=1;
elseif substr(s,1,4) mod 100 = 0 then set bisiesto=0;
elseif substr(s,1,4) mod 4 = 0 then set bisiesto=1;
else set bisiesto=0;
end if;

set tp=
(case when substr(s, 7,2)<=
case substr(s, 5,2)
when '01' then 31
when '02' then
case when bisiesto=1 then 29 else 28 end /*si el anno es bisiesto febrero tiene 29 dias*/
when '03' then 31
when '04' then 30
when '05' then 31
when '06' then 30
when '07' then 31
when '08' then 31
when '09' then 30
when '10' then 31
when '11' then 30
when '12' then 31
else 0 end
and substr(s, 7,2)>0
then 1 else 0 end);

return tp;

END $$

Posted by Paris Alex on November 19, 2008

I've always find it useful to be able to find out the number of records created on a monthly basis. This SELECT statement does the job by formatting a date field using DATE_FORMAT() and group it to see data by the year and month.

SELECT DATE_FORMAT(creationDate, '%Y-%m') AS month, COUNT(*) AS total FROM myTable GROUP BY month ORDER BY total DESC LIMIT 5;

+---------+-------+
| month   | total |
+---------+-------+
| 2006-07 |   485 | 
| 2006-08 |   179 | 
| 2008-10 |    96 | 
| 2008-06 |    89 | 
| 2008-01 |    84 | 
+---------+-------+

5 rows in set (0.00 sec)

The ORDER BY and LIMIT is optional, to further filter the select statement.

Regards,
Alex
http://www.loveromehotel.com/

Posted by Joao Marques Gomes on February 6, 2009

Get first day of current week. When first day is a Sunday:

select date_sub(curdate(), interval dayofweek(curdate()) -1 day)

Joao

Posted by Loreto Parisi on February 8, 2009

I found function str_to_date() very useful when having "human readable" date formats and you want to use the ORDER BY clause to sort the table by those fields:

Supposed we have a fields 'published_date' like this:

SELECT [,] published_date [,]

+---------------------------------+
| published_date                  |
+---------------------------------+
| Fri, 23 Jan 2009 00:00:00 -0800 | 
| Mon, 26 Jan 2009 02:21:09 -0800 | 
| Fri, 23 Jan 2009 16:00:00 -0800 | 
| Thu, 22 Jan 2009 15:00:00 -0800 | 
| Thu, 29 Jan 2009 02:00:27 -0800 | 
+---------------------------------+

Now we try to ORDER BY published_date DESC, resulting in:

SELECT [,] published_date [,] ORDER BY published_date DESC []

+---------------------------------+
| published_date                  |
+---------------------------------+
| Wed, 21 Jan 2009 18:30:00 -0800 | 
| Wed, 21 Jan 2009 11:30:36 -0800 | 
| Tue, 27 Jan 2009 00:09:46 -0800 | 
| Tue, 20 Jan 2009 16:00:00 -0800 | 
| Tue, 13 Jan 2009 16:00:00 -0800 | 
+---------------------------------+

As you can see the set is not well sorted , So simply use the str_to_date fun with the syntax:

SELECT [,] str_to_date(published_date,'%a, %d %b %Y %H:%i:%s') as my_published_date [,] ORDER BY my_published_date DESC []

So we'll have:

+---------------------+
| my_published_date   |
+---------------------+
| 2009-01-30 11:39:04 | 
| 2009-01-29 10:26:51 | 
| 2009-01-29 02:00:27 | 
| 2009-01-27 00:09:46 | 
| 2009-01-26 08:10:45 | 
+---------------------+

and the set is now sorted well.

Posted by Steven Copley on March 26, 2009

This will give week days (everything minus weekends) between 2 dates :

SELECT
(floor( datediff( '2009-01-11', '2009-01-01' ) /7 ) *5) +
CASE dayofweek('2009-01-01')
WHEN 1 THEN mod(datediff( '2009-01-11', '2009-01-01' ) , 7) - 2
WHEN 7 THEN mod(datediff( '2009-01-11', '2009-01-01' ) , 7) - 1
ELSE
LEAST(7-dayofweek( '2009-01-01' ), mod(datediff( '2009-01-11', '2009-01-01' ) , 7))
END;

Posted by Joshua Lebo on May 19, 2009

Another way to find the last day of a month (without LAST_DAY), given a date within that month:

select date_sub(concat(date_format(date_add( curdate(), interval 1 month), '%Y-%m'), '-01'), INTERVAL 1 DAY) ;

or for a specific day:

select date_sub(concat(date_format(date_add( '2008-02-18', interval 1 month), '%Y-%m'), '-01'), INTERVAL 1 DAY) ;

walks to the first of the following month, then subtracts 1 day

Posted by Daniel Berstein on June 23, 2009

To find future date in X business days, took me a while but here it is without using store procedures, instead I compute the number of weekends between the initial date and date + X days, adjust for the weekend days. Its implemented as a derived table to easy joins with real tables.
<code>
/* The initial date from when to start counting */
SET @start := NOW();
/* Number of business days */
SET @days := 4;
/* The query */
SELECT calendar.`Result`
FROM (
/* If initial date is on a weekend, adjust to first business day */
SELECT @start := @start + INTERVAL CASE WHEN DAYOFWEEK(@start) = 7 THEN 2 WHEN DAYOFWEEK(@start) = 1 THEN 1 ELSE 0 END DAY `First`,
@days `Days`,
/* Number of estimated business weeks */
@weekends := DATEDIFF(@start + INTERVAL @days DAY, @start) DIV 5 `Weekends`,
/* Estimated target date based number of weekends */
@guess := @start + INTERVAL @days + 2*@weekends DAY `Guess`,
/* Adjust result date if it falls on a weekend */
IF (DAYOFWEEK(@guess) = 1, @guess + INTERVAL 1 DAY, IF (DAYOFWEEK(@guess) = 7, @guess + INTERVAL + 2 DAY, @guess)) `Result`
) calendar;
</code>

Posted by Martin Stjernholm on August 3, 2009

To expand a bit on the note by Jeffrey Friedl on October 31 2004 9:05am:

The manual states that FROM_UNIXTIME(UNIX_TIMESTAMP(...)) doesn't map back to the same formatted date. What also should be stated is that the reverse is not true either.

UNIX_TIMESTAMP(ts) where ts is a TIMESTAMP column returns the unix timestamp stored in it without conversion to/from a formatted date string. That avoids trouble with timezones and DST overlaps etc.

However, when the column ts is set through FROM_UNIXTIME(n), it (apparently) formats the unix timestamp as a string which is then parsed back to a timestamp again. The formatting and the parsing is done with the same time zone, so the timezone offsets generally cancel themselves out. The exception is if the timezone uses DST and the timestamp is in the overlapping hour in the fall when going from summer time to normal time.

E.g. if the active time zone on the connection is Central European Time, which uses DST, then setting 1130630400 (Sun 30 Oct 2005 2:00:00 CEST) through

INSERT INTO foo SET ts = FROM_UNIXTIME(1130630400)

actually sets the ts column to 1130634000 (Sun 30 Oct 2005 2:00:00 CET), i.e one hour later.

The only way around that problem is apparently to ensure that the time zone used on the connection is one which doesn't use DST. E.g. UTC is a reasonable choice, which can be set on the connection through "SET time_zone = '+00:00'".

Posted by Werner Kremer on August 4, 2009

I implemented a well known algorithm from an English standards organisation (I've forgotten exactly who).

for the calculate easter sunday i used following function:

DELIMITER $$

USE `pczeitdb`$$

DROP FUNCTION IF EXISTS `fneastern`$$

CREATE DEFINER=`wkroot`@`%` FUNCTION `fneastern`(iYear INT) RETURNS DATE
DETERMINISTIC
BEGIN
SET @iD=0,@iE=0,@iQ=0,@iMonth=0,@iDay=0;

SET @iD = 255 - 11 * (iYear % 19);
SET @iD = IF (@iD > 50,(@iD-21) % 30 + 21,@iD);
SET @iD = @iD - IF(@iD > 48, 1 ,0);
SET @iE = (iYear + FLOOR(iYear/4) + @iD + 1) % 7;
SET @iQ = @iD + 7 - @iE;
IF @iQ < 32 THEN
SET @iMonth = 3;
SET @iDay = @iQ;
ELSE
SET @iMonth = 4;
SET @iDay = @iQ - 31;
END IF;

RETURN STR_TO_DATE(CONCAT(iYear,'-',@iMonth,'-',@iDay),'%Y-%m-%d');
END$$

DELIMITER ;

Posted by Ben Short on September 16, 2009

Benjamin Zagel's posting on getting the last day of the month needs tweaking: it incorrectly told me that the last day of the month was 28th of March. This is easily remedied - simply swap the order ie. add Month First, THEN subtract a day:

ie:

SELECT DATE_FORMAT('2009-03-16' ,'%Y-%m-01') as First, (DATE_FORMAT('2009-03-16' ,'%Y-%m-01') + INTERVAL 1 MONTH) - INTERVAL 1 DAY AS Last;

(Date functions are not commutative).

Posted by Andy Schmidt on November 7, 2009

I didn't find a format variable to output the ISO timezone offset "+/-HHMM", as required for RSS, SMTP or HTTP headers, etc.

The following will output the proper full-hour offset from UTC:

SELECT TIME_FORMAT( NOW() - UTC_TIMESTAMP(), '%H%i' ) AS tz_offset;

Posted by John Doe on December 21, 2009

This is a SQL statement to list all the people whose birthday is coming up in the next couple of weeks, paying attention to year's end:

SET @YEAR = EXTRACT(YEAR FROM CURDATE());

SELECT name FROM mytable WHERE DATEDIFF(DATE_FORMAT(birthdate,CONCAT(@YEAR,"-%m-%d")),CURDATE()) BETWEEN 0 AND 15 OR DATEDIFF(DATE_FORMAT(birthdate,CONCAT(@YEAR + 1,"-%m-%d")),CURDATE()) BETWEEN 0 AND 15;

Posted by Rick Wellman on January 5, 2010

Much appreciation to Steven Copley's post concerning weekdays [since that is what I was looking for] but I think he used the dayofweek() function where he meant to use the weekday() function in the LEAST() clause. i.e.

This will give week days (everything minus weekends) between 2 dates :

SELECT
(floor( datediff( '2009-01-11', '2009-01-01' ) /7 ) *5) +
CASE dayofweek('2009-01-01')
WHEN 1 THEN mod(datediff( '2009-01-11', '2009-01-01' ) , 7) - 2
WHEN 7 THEN mod(datediff( '2009-01-11', '2009-01-01' ) , 7) - 1
ELSE
LEAST(7-weekday( '2009-01-01' ), mod(datediff( '2009-01-11', '2009-01-01' ) , 7))
END;

Posted by Robert Eisele on January 15, 2010

I discussed the topic of age calculation two weeks before on my blog: http://www.xarg.org/2009/12/age-calculation-with-mysql/

I found a very smart solution to calculate the age from a DATE value:

CREATE FUNCTION getage(BDAY DATE)
RETURNS TINYINT UNSIGNED
RETURN YEAR(FROM_DAYS(DATEDIFF(NOW(), BDAY)))

To calculate someones next birthday, I wrote a similar function:

CREATE DFUNCTION nextbday(bday DATE)
RETURNS DATE
RETURN DATE_ADD(bday, INTERVAL YEAR(FROM_DAYS(DATEDIFF(NOW(), bday) - 1)) + 1 YEAR)

Posted by Michael Cunningham on January 24, 2010

I personally got stuck, trying to feed VBScript dates back into MySQL; as the ODBC Driver converts the MySQL dates to VBScript's version automatically.

This is a one-liner solution for everyone using VBScript (ASP), that needs to feed a VB date into MySQL.

Input: REQmod in any date format that VBScript understands (1/1/1970 12:00:01 AM)

REQmod = year(REQmod) & "-" & right("0" & month(REQmod),2) & "-" & right("0" & day(REQmod),2) & " " & right("0" & Hour(REQmod),2) & ":" & right("0" & Minute(REQmod),2) & ":" & right("0" & Second(REQmod),2)

Output: REQmod will be strictly in MySQL Format (1970-01-01 00:00:01)

Posted by D. Meanea on May 4, 2010

Two things to keep in mind when using the TIMESTAMPDIFF function:

1. The function returns a truncated integer of the specified unit. It does NOT use the unit to determine the precision of the difference calculation. For example, you might expect
SELECT TIMESTAMPDIFF(MONTH,'2010-03-31','2010-04-30');
to return 1, as the difference between '2010-03' and '2010-04'. However, because the difference (including the days) is not quite a full month, it returns 0, not 1.

2. In version 5.0, the unit you specify determines whether the calculation includes the time elements. When using the YEAR or MONTH units, the function uses the date elements (year, month and day) in the comparison, but ignores the time elements. For example,
SELECT TIMESTAMPDIFF(MONTH,'2010-03-01 00:00:00','2010-04-01 00:00:00');
and
SELECT TIMESTAMPDIFF(MONTH,'2010-03-01 23:59:59','2010-04-01 00:00:00');
both return 1, while
SELECT TIMESTAMPDIFF(MONTH,'2010-03-02 00:00:00','2010-04-01 00:00:00');
returns 0.

However, if you use DAY as the unit, all date and time elements are included in the calculation. Thus,
SELECT TIMESTAMPDIFF(DAY,'2010-03-29 00:00:00','2010-03-30 00:00:00');
returns 1, while
SELECT TIMESTAMPDIFF(DAY,'2010-03-29 00:00:01','2010-03-30 00:00:00');
returns 0.

In version 5.1, the function includes the time elements in all calculations. (My testing was done in versions 5.0.75 and 5.1.30)

This function works fine for calculations on the time part of a timestamp; but for working with the date part, I much prefer using the YEAR, PERIOD_DIFF, or TO_DAYS functions.

Posted by Stoob ! on May 12, 2010

If you have a VARCHAR column called, for example, `Date` that contains date data, but is not formatted as a MySQL DATE column, you can convert it using MySQL's STR_TO_DATE function.

For instance, Excel stores can store dates like this 1/31/2010. MySQL uses this, 2010-01-31.

Step 1.
Create a column of type DATE called `MySQLDate`

Step 2.
UPDATE `table` SET MySQLDate = (SELECT STR_TO_DATE(`Date`,'%c/%e/%Y'));

Also here is another tip. There is a LAST_DAY() function but no FIRST_DAY() function. This has the same effect of FIRST_DAY: it subtracts a month, find last day, and then add 1 day.

UPDATE `table` SET start_date = DATE_ADD(LAST_DAY(DATE_SUB(start_date, INTERVAL 1 MONTH)), INTERVAL 1 DAY);

Posted by Sankar Ramanathan on July 2, 2010

To find number of days in a month.

SELECT DAY(LAST_DAY('2010-02-1'));
or
SELECT DAYOFMONTH(LAST_DAY('2010-02-01'));

Posted by nicolas lumbreras on October 5, 2010

CREATE FUNCTION `workdayadd`(a date, days int) RETURNS date
DETERMINISTIC
COMMENT 'add workdays to date a'
BEGIN
DECLARE freedays int;
DECLARE daysadd, totaldays, workday, di INT;
declare dateinit date;

set dateinit=a;
SET workday=0;
SET di=DAYOFWEEK(dateinit);
set totaldays = 0;

WHILE workday<=days DO
if (di=8) then
set di=1;
end if;
IF (di>1 and di<7) THEN
SET workday=(workday+1);
END IF;
SET di=(di+1);
SET totaldays=(totaldays+1);
END WHILE;
if di<=2 then
set totaldays=totaldays-di;
end if;

set daysadd=totaldays;

while daysadd>0 do
SELECT count(*) INTO freedays
FROM holliday
WHERE d_day BETWEEN dateinit AND date_add(dateinit,interval daysadd-1 day)
AND WEEKDAY(d_day)<5;

if freedays>0 then
SET workday=0;
set dateinit=date_add(dateinit,interval daysadd day);
SET di=DAYOFWEEK(dateinit);
WHILE workday<freedays DO
if (di=8) then
set di=1;
end if;
IF (di>1 and di<7) THEN
SET workday=(workday+1);
END IF;
SET di=(di+1);
SET totaldays=(totaldays+1);
END WHILE;
if di<=2 then
set totaldays=totaldays-di;
end if;
end if;
set daysadd = freedays;
end while;
return date_add(a, interval (totaldays-1) day);
END;

Posted by Neil Hopkins on December 2, 2010

For those looking for a WEEKOFMONTH function:

mysql> SELECT 1 + WEEK(STR_TO_DATE('12/2/2010 11:00:00 AM','%m/%d/%Y %h:%i:%s %p')) - WEEK(DATE_ADD(LAST_DAY(DATE_SUB(STR_TO_DATE('12/2/2010 11:00:00 AM','%m/%d/%Y %h:%i:%s %p'), INTERVAL '1' MONTH)), INTERVAL '1' DAY))
FROM DUAL;

-> 1

Posted by John Burr on December 17, 2010

To calculate the difference between any two dates or times when you want to specify the units (i.e. years, months, weeks, hours, minutes, etc.) just use the TIMESTAMPDIFF function. That's what was designed and optimized to do this.

To calculate the age of all the participants in my table, my SELECT query looks like:

SELECT name_first, name_last, TIMESTAMPDIFF(YEAR, birthdate, CURDATE()) FROM participants;

Posted by Patrick Renaud on April 5, 2011

Please note the TIMEDIFF function is limited to the following range : [-839h 59m 59s ; +839h 59m 59s].
The same stands for SEC_TO_TIME.

Posted by bob lawn on April 21, 2011

Further to Santi Bari's excellent suggestion to "plug the missing gaps", remember that if you have additional clauses in your retrieval, you may have to include a little extra in your syntax.

For example, following on from Santi's example, suppose you had a field in the visits table for capturing the browser used.
To retrieve the data where the browser was Firefox, you would add a WHERE clause, like :
WHERE visits.browser = 'Firefox'

However, this will not work as expected. To plug the holes in the dates, the right syntax would be :
WHERE (visits.browser = 'Firefox' OR visits.browser IS NULL)

and the gaps in the dates will be filled again!

Posted by Serg Kalachev on April 22, 2011

Using function from Martin Minka posted here on January 25 2007 5:23pm in this example we calculate effective working minutes elapsed between creation and completion of ServiceDesk request. I hope it may be useful...

SELECT `created_at` , `finished_at` ,
CASE mysql.workdaydiff( `finished_at` , `created_at`)
WHEN 1 THEN TIMESTAMPDIFF( MINUTE , `created_at` , `finished_at` )
ELSE
( mysql.workdaydiff(`finished_at` , `created_at`) -2
) *60 *9 +
TIMESTAMPDIFF( MINUTE , `created_at` , DATE_ADD( DATE( `created_at` ) , INTERVAL 19 HOUR ) ) +
TIMESTAMPDIFF( MINUTE , DATE_ADD( DATE( `finished_at` ) , INTERVAL 10 HOUR ) , `finished_at` )
END AS working_time_used_to_finish_request
FROM `request`
WHERE `request_status_id` IN ( 4, 5 )

Posted by Mustali Kachwala on April 29, 2011

An example on date_sub to get report for last 7 days

http://mustalikachwala.blogspot.com/2011/04/mysql-query-to-get-data-for-last-7-days.html

Posted by shivam sharma on October 31, 2011

Hello All,

Here are two methods to find first day of month:

SELECT DATE_SUB(LAST_DAY(NOW()),INTERVAL DAY(LAST_DAY(NOW()))-1 DAY)

SELECT DATE_SUB(NOW(),INTERVAL DAY(NOW())-1 DAY)

Hope these will be helpful to you ... :)

Posted by SANATAN OJHA on February 2, 2012

This is simple example wrriten in sql to get date difference in year month day

CREATE TABLE temp_rent_ftth_a (
rent_upto date DEFAULT NULL,
bill_to date DEFAULT NULL,
billy int(4) DEFAULT NULL,
billm int(2) DEFAULT NULL,
billd int(2) DEFAULT NULL,
renty int(4) DEFAULT NULL,
rentm int(2) DEFAULT NULL,
rentd int(2) DEFAULT NULL);
insert into temp_rent_ftth_a (rent_upto,bill_to) values ('2012-02-02','1967-06-10');
update temp_rent_ftth_a set renty=year(rent_upto),rentm=month(rent_upto),rentd=day(rent_upto);
update temp_rent_ftth_a set billy=year(bill_to),billm=month(bill_to),billd=day(bill_to);
update temp_rent_ftth_a set rentd=rentd+30 where rentd<billd;
update temp_rent_ftth_a set rentm=rentm-1 where rentd-30<billd;
update temp_rent_ftth_a set rentm=rentm+12 where rentm+1<billm;
update temp_rent_ftth_a set renty=renty-1 where rentm-12<billm;
select rentd-billd,rentm-billm,renty-billy from temp_rent_ftth_a;

Posted by Denis Kukharev on May 17, 2012

If you need to access LAST_INSERT_ID() outside a trigger where it has been modified, you can use workaround with user-defined variable that is to be assigned with LAST_INSERT_ID() inside the trigger.
This implies an overhead of additional query to read the variable, but it seems to be the only way to solve the problem.

Posted by Luis Lobo Borobia on June 8, 2012

When you need to get the timestamp of a date in a certain timezone or GMT time, use this:

select
UNIX_TIMESTAMP(
CONVERT_TZ( '2012-05-31 23:59:59',
'-03:00',
'+00:00') ) + TIMESTAMPDIFF(second,utc_timestamp(), now()) as time;

This will return the UTC timestamp for the datetime in Argentina at 23:59:59, GMT-3.

A generic way of getting the UTC time of a certain LOCAL DATE TIME is:

select
UNIX_TIMESTAMP(
CONVERT_TZ( '2012-05-31 23:59:59',
substring(
replace(
concat('+',
SEC_TO_TIME( TIMESTAMPDIFF( second,utc_timestamp(), now() ) )
)
,'+-','-')
,1,6),
'+00:00') ) + TIMESTAMPDIFF(second,utc_timestamp(), now()) as time;

Posted by Dennis German on July 6, 2012

Don't use %l format (lower case L; 1..12) for hours as a result of SUBTIME since
select Time_Format( SUBTIME('20:16:44', '20:05:20') , '%l:%i');
results in 12:11 rather than the 00:11 you might have expected.

Posted by John Long on February 5, 2013

Just aggregating some of what I found on this page in a single query.

SELECT
-- DAY OF LAST WEEK - LAST YEAR
DATE_SUB((CURRENT_DATE - INTERVAL 1 YEAR),INTERVAL WEEKDAY((CURRENT_DATE - INTERVAL 1 YEAR)) +7 DAY) LAST_YEAR_LAST_WK_MONDAY,
DATE_SUB((CURRENT_DATE - INTERVAL 1 YEAR),INTERVAL WEEKDAY((CURRENT_DATE - INTERVAL 1 YEAR)) +6 DAY) LAST_YEAR_LAST_WK_TUESDAY,
DATE_SUB((CURRENT_DATE - INTERVAL 1 YEAR),INTERVAL WEEKDAY((CURRENT_DATE - INTERVAL 1 YEAR)) +5 DAY) LAST_YEAR_LAST_WK_WEDNESDAY,
DATE_SUB((CURRENT_DATE - INTERVAL 1 YEAR),INTERVAL WEEKDAY((CURRENT_DATE - INTERVAL 1 YEAR)) +4 DAY) LAST_YEAR_LAST_WK_THURSDAY,
DATE_SUB((CURRENT_DATE - INTERVAL 1 YEAR),INTERVAL WEEKDAY((CURRENT_DATE - INTERVAL 1 YEAR)) +3 DAY) LAST_YEAR_LAST_WK_FRIDAY,
DATE_SUB((CURRENT_DATE - INTERVAL 1 YEAR),INTERVAL WEEKDAY((CURRENT_DATE - INTERVAL 1 YEAR)) +2 DAY) LAST_YEAR_LAST_WK_SATURDAY,
DATE_SUB((CURRENT_DATE - INTERVAL 1 YEAR),INTERVAL WEEKDAY((CURRENT_DATE - INTERVAL 1 YEAR)) +1 DAY) LAST_YEAR_LAST_WK_SUNDAY,
--
-- DAY OF THIS WEEK - LAST YEAR
DATE_SUB((CURRENT_DATE - INTERVAL 1 YEAR),INTERVAL WEEKDAY((CURRENT_DATE - INTERVAL 1 YEAR)) -0 DAY) LAST_YEAR_THIS_WK_MONDAY,
DATE_SUB((CURRENT_DATE - INTERVAL 1 YEAR),INTERVAL WEEKDAY((CURRENT_DATE - INTERVAL 1 YEAR)) -1 DAY) LAST_YEAR_THIS_WK_TUESDAY,
DATE_SUB((CURRENT_DATE - INTERVAL 1 YEAR),INTERVAL WEEKDAY((CURRENT_DATE - INTERVAL 1 YEAR)) -2 DAY) LAST_YEAR_THIS_WK_WEDNESDAY,
DATE_SUB((CURRENT_DATE - INTERVAL 1 YEAR),INTERVAL WEEKDAY((CURRENT_DATE - INTERVAL 1 YEAR)) -3 DAY) LAST_YEAR_THIS_WK_THURSDAY,
DATE_SUB((CURRENT_DATE - INTERVAL 1 YEAR),INTERVAL WEEKDAY((CURRENT_DATE - INTERVAL 1 YEAR)) -4 DAY) LAST_YEAR_THIS_WK_FRIDAY,
DATE_SUB((CURRENT_DATE - INTERVAL 1 YEAR),INTERVAL WEEKDAY((CURRENT_DATE - INTERVAL 1 YEAR)) -5 DAY) LAST_YEAR_THIS_WK_SATURDAY,
DATE_SUB((CURRENT_DATE - INTERVAL 1 YEAR),INTERVAL WEEKDAY((CURRENT_DATE - INTERVAL 1 YEAR)) -6 DAY) LAST_YEAR_THIS_WK_SUNDAY,
--
-- DAY OF LAST WEEK - THIS YEAR
DATE_SUB(CURDATE(),INTERVAL WEEKDAY(CURDATE()) +7 DAY) LAST_WK_MONDAY,
DATE_SUB(CURDATE(),INTERVAL WEEKDAY(CURDATE()) +6 DAY) LAST_WK_TUESDAY,
DATE_SUB(CURDATE(),INTERVAL WEEKDAY(CURDATE()) +5 DAY) LAST_WK_WEDNESDAY,
DATE_SUB(CURDATE(),INTERVAL WEEKDAY(CURDATE()) +4 DAY) LAST_WK_THURSDAY,
DATE_SUB(CURDATE(),INTERVAL WEEKDAY(CURDATE()) +3 DAY) LAST_WK_FRIDAY,
DATE_SUB(CURDATE(),INTERVAL WEEKDAY(CURDATE()) +2 DAY) LAST_WK_SATURDAY,
DATE_SUB(CURDATE(),INTERVAL WEEKDAY(CURDATE()) +1 DAY) LAST_WK_SUNDAY,
--
-- DAY OF CURRENT WEEK - THIS YEAR
DATE_SUB(CURDATE(),INTERVAL WEEKDAY(CURDATE()) -0 DAY) CUR_WK_MONDAY,
DATE_SUB(CURDATE(),INTERVAL WEEKDAY(CURDATE()) -1 DAY) CUR_WK_TUESDAY,
DATE_SUB(CURDATE(),INTERVAL WEEKDAY(CURDATE()) -2 DAY) CUR_WK_WEDNESDAY,
DATE_SUB(CURDATE(),INTERVAL WEEKDAY(CURDATE()) -3 DAY) CUR_WK_THURSDAY,
DATE_SUB(CURDATE(),INTERVAL WEEKDAY(CURDATE()) -4 DAY) CUR_WK_FRIDAY,
DATE_SUB(CURDATE(),INTERVAL WEEKDAY(CURDATE()) -5 DAY) CUR_WK_SATURDAY,
DATE_SUB(CURDATE(),INTERVAL WEEKDAY(CURDATE()) -6 DAY) CUR_WK_SUNDAY,
--
-- DAY OF NEXT WEEK - THIS YEAR
DATE_SUB(CURDATE(),INTERVAL WEEKDAY(CURDATE()) -7 DAY) NEXT_WK_MONDAY,
DATE_SUB(CURDATE(),INTERVAL WEEKDAY(CURDATE()) -8 DAY) NEXT_WK_TUESDAY,
DATE_SUB(CURDATE(),INTERVAL WEEKDAY(CURDATE()) -9 DAY) NEXT_WK_WEDNESDAY,
DATE_SUB(CURDATE(),INTERVAL WEEKDAY(CURDATE()) -10 DAY) NEXT_WK_THURSDAY,
DATE_SUB(CURDATE(),INTERVAL WEEKDAY(CURDATE()) -11 DAY) NEXT_WK_FRIDAY,
DATE_SUB(CURDATE(),INTERVAL WEEKDAY(CURDATE()) -12 DAY) NEXT_WK_SATURDAY,
DATE_SUB(CURDATE(),INTERVAL WEEKDAY(CURDATE()) -13 DAY) NEXT_WK_SUNDAY,
--
-- FIRST AND LAST OF MONTH --
DATE_FORMAT( CURRENT_DATE - INTERVAL 1 MONTH, '%Y-%m-01') LAST_MON_START,
LAST_DAY(CURRENT_DATE - INTERVAL 1 MONTH) LAST_MONTH_END,
DATE_FORMAT( CURRENT_DATE, '%Y-%m-01' ) THIS_MON_START,
LAST_DAY(SYSDATE()) THIS_MONTH_END,
DATE_FORMAT( CURRENT_DATE + INTERVAL 1 MONTH, '%Y-%m-01') NEXT_MON_START,
LAST_DAY(CURRENT_DATE + INTERVAL 1 MONTH) NEXT_MONTH_END,
--
-- LAST YEAR, THIS YEAR, NEXT YEAR
YEAR(CURRENT_DATE - INTERVAL 1 YEAR) LAST_YEAR,
YEAR(CURRENT_DATE) CURRENT_YEAR,
YEAR(CURRENT_DATE + INTERVAL 1 YEAR) NEXT_YEAR,
--
DATE_FORMAT( CURRENT_DATE, '%Y-01-01') FIRST_DAY_OF_CUR_YEAR,
DATE_FORMAT( CURRENT_DATE, '%Y-12-31') LAST_DAY_OF_CUR_YEAR
;

Posted by Lyle Brewer on February 10, 2013

Calculating age in years from date of birth accurately using datediff() doesn't work due to leap years. If you calcualte a person's age on a date near their birthday, you're likely to get an incorrect result. The older the subject is, the more likely you will get an incorrect result due to the number of leap years that has occurred in a person's life. For example, a person who is 100 has lived through about 25 leap years.

Calculating age is a simple problem. It boils down to subtracting year of birth from the current year (or whatever year you're calculating age at) and then subtractiing 1 if the subject's birth date is after the the date of the calculation in the calendar year of the date of calculation. For example, if the subject was born on June 15th, 1954 and you're calculating their age on July 1st, 1984, then their birthday has already occurred in the calendar year of the date of calculation and the correct answer is 1984 - 1954 = 30. That calculation works if the subject's birth date is on or before the date of calculation. However, if that person were born on August 1st, 1954, then their birthday occurs later in the calendar year than the date of calculation. In that case, the person is still only 29 on July 1st which means that the correct caclulation is 1984 - 1954 - 1 = 29.

To calculate age in years accurately, you need a calculation which simply subtracts the year of the date of birth from the year of the date of calculation and then adds "- 1" to the calculation if the person's birthday occurs after the date of calculation in the calender year of the date of calculation. I was able to get a 100% correct answer using a nested if-then-else function. However, the simplest approach I've come across is actually in this reference manual here:

http://dev.mysql.com/doc/refman/5.5/en/date-calculations.html

It does the same thing as my more complicated if-then-else approach but it's a lot simpler. Stay away from the datediff() approaches for calculating age. This approach is 100% accurate. It will even give you the correct age, in years, for someone born on February 29th.

Posted by Lyle Brewer on February 12, 2013

Paul Dubois of Oracle emailed me with the following comment:

If you're doing age calculations, wouldn't you be better off using
TIMESTAMPDIFF(YEAR,date1,date2) ?

I tried it and it works like a charm. I tested an age calculation against today's date, 2013-02-12, using the birthdates 1911-02-12 (birthday today) and 1911-02-13 (birhtday tomorrow). It returned the correct results of 102 for 1911-02-12 (birthday today) and 101 for 1911-02-13 (birthday tomorrow).

Posted by ALEXANDER SKAKUNOV on March 21, 2013

If you have a queue and you want to find out the average time in which an item gets processed, you can use this snippet (that's what we use for a dashboard in our http://yasno.tv/ project).

If you have a table of queued items with `created_at` and `updated_at` datetime fields that represent when an item was added and when it was updated (processed) accordingly. So,

[code]
SELECT SEC_TO_TIME(AVG(TIME_TO_SEC(TIMEDIFF(`updated_at`, `created_at`)))) AS average_item_time
FROM `mail_queue_item`
[/code]

shows something like "00:02:30" which means average idle time is 2.5 minutes per item.

Posted by Programmer Old on April 16, 2013

In our database there are partial dates. In spite of ALLOW_INVALID_DATES function DATEDIFF yields NULL on them. Therefore, I wrote this function:

CREATE FUNCTION ddiff(lait DATE, earlie DATE) RETURNS INTEGER(7)
COMMENT 'less pickie dait-differens'
DETERMINISTIC
RETURN ROUND(PERIOD_DIFF(EXTRACT(YEAR_MONTH FROM lait), EXTRACT(YEAR_MONTH FROM earlie)) * 30.44) + DAY(lait) - DAY(earlie)

It is at most 2 days off the real difference, and the greatly biassed value for DAY(d) = 0 is of little importance in our case. If it mattered, we would make it 15.

Posted by Rick James on November 27, 2013

When did MySQL restart?
SELECT NOW() - INTERVAL VARIABLE_VALUE SECOND
FROM information_schema. GLOBAL_STATUS
WHERE VARIABLE_NAME = 'UPTIME';
--> 2013-11-16 10:07:47

Or, simply the date:
SELECT DATE(NOW() - INTERVAL VARIABLE_VALUE SECOND) AS StartDate
FROM information_schema. GLOBAL_STATUS
WHERE VARIABLE_NAME = 'UPTIME';
--> 2013-11-16

Posted by Chris Wilson on August 15, 2014

The query cache can cause CONVERT_TZ to return invalid results (NULL) even after the timezone data has been loaded, because loading these tables does not properly invalidate the cache. http://bugs.mysql.com/73604.

Posted by Adolfo adolfo on February 11, 2015

Function like Date_add considering only business's day (Monday-Friday)

delimiter $
drop function if exists BusinessDaysDateAdd
$
create function BusinessDaysDateAdd
(
...FromDate datetime,
...DaysToAdd int
)
RETURNS datetime
BEGIN
...SET @Result = (FromDate + interval floor(DaysToAdd / 5) week) +
.............................interval (mod(DaysToAdd,5) +
......................................(CASE mod(DAYOFWEEK(FromDate) + mod(DaysToAdd,5),7)
..........................................WHEN 0 THEN 2
..........................................WHEN 1 THEN 2
..........................................ELSE 0 END)) day;
...RETURN @Result;
END;
$

delimiter ;