TIMESTAMP types are related. This section
describes their characteristics, how they are similar, and how
they differ. MySQL recognizes
values in several formats, described in
Section 9.1.3, “Date and Time Literals”. For the
descriptions, “supported” means that although
earlier values might work, there is no guarantee.
DATE type is used for values with a date
part but no time part. MySQL retrieves and displays
DATE values in
'YYYY-MM-DD' format. The supported range is
DATETIME type is used for values that
contain both date and time parts. MySQL retrieves and displays
DATETIME values in
HH:MM:SS' format. The supported range is
'1000-01-01 00:00:00' to
TIMESTAMP data type is used for values
that contain both date and time parts.
TIMESTAMP has a range of
00:00:01' UTC to
value can include a trailing fractional seconds part in up to
microseconds (6 digits) precision. In particular, any fractional
part in a value inserted into a
TIMESTAMP column is stored rather than
discarded. With the fractional part included, the format for
these values is
HH:MM:SS[.fraction]', the range for
DATETIME values is
23:59:59.999999', and the range for
TIMESTAMP values is
03:14:07.999999'. The fractional part should always be
separated from the rest of the time by a decimal point; no other
fractional seconds delimiter is recognized. For information
about fractional seconds support in MySQL, see
Section 11.3.6, “Fractional Seconds in Time Values”.
data types offer automatic initialization and updating to the
current date and time. For more information, see
Section 11.3.5, “Automatic Initialization and Updating for TIMESTAMP and DATETIME”.
TIMESTAMP values from the
current time zone to UTC for storage, and back from UTC to the
current time zone for retrieval. (This does not occur for other
types such as
DATETIME.) By default, the
current time zone for each connection is the server's time. The
time zone can be set on a per-connection basis. As long as the
time zone setting remains constant, you get back the same value
you store. If you store a
and then change the time zone and retrieve the value, the
retrieved value is different from the value you stored. This
occurs because the same time zone was not used for conversion in
both directions. The current time zone is available as the value
variable. For more information, see
Section 10.6, “MySQL Server Time Zone Support”.
TIMESTAMP values are converted to the
“zero” value of the appropriate type
Be aware of certain properties of date value interpretation in MySQL:
MySQL permits a “relaxed” format for values
specified as strings, in which any punctuation character may
be used as the delimiter between date parts or time parts.
In some cases, this syntax can be deceiving. For example, a
value such as
'10:11:12' might look like
a time value because of the
:” delimiter, but is
interpreted as the year
used in a date context. The value
'10:45:15' is converted to
'45' is not a valid month.
The only delimiter recognized between a date and time part and a fractional seconds part is the decimal point.
The server requires that month and day values be valid, and
not merely in the range 1 to 12 and 1 to 31, respectively.
With strict mode disabled, invalid dates such as
'2004-04-31' are converted to
'0000-00-00' and a warning is generated.
With strict mode enabled, invalid dates generate an error.
To permit such dates, enable
Section 5.1.7, “Server SQL Modes”, for more information.
MySQL does not accept
that include a zero in the day or month column or values
that are not a valid date. The sole exception to this rule
is the special “zero” value
Dates containing two-digit year values are ambiguous because the century is unknown. MySQL interprets two-digit year values using these rules:
Year values in the range
Year values in the range
The MySQL server can be run with the
MAXDB SQL mode enabled. In
TIMESTAMP is identical with
DATETIME. If this mode is enabled at the
time that a table is created,
columns are created as
DATETIME columns. As
a result, such columns use
format, have the same range of values, and there is no
automatic initialization or updating to the current date and
time. See Section 5.1.7, “Server SQL Modes”.