MySQL 5.6 リファレンスマニュアル  /  関数と演算子  /  日付および時間関数

12.7 日付および時間関数

このセクションでは、時間値の処理に使用できる関数について説明します。各日付日時型が持つ値の範囲、および値を指定する際の有効な書式については、セクション11.3「日付と時間型」を参照してください。

表 12.13 日付/時間関数

名前 説明
ADDDATE() 日付値に時間値 (間隔) を加算します
ADDTIME() 時間を加算します
CONVERT_TZ() あるタイムゾーンから別のタイムゾーンに変換します
CURDATE() 現在の日付を返します
CURRENT_DATE(), CURRENT_DATE CURDATE() のシノニムです
CURRENT_TIME(), CURRENT_TIME CURTIME() のシノニムです
CURRENT_TIMESTAMP(), CURRENT_TIMESTAMP NOW() のシノニムです
CURTIME() 現在の時間を返します
DATE() 日付または日付時間式の日付部分を抽出します
DATE_ADD() 日付値に時間値 (間隔) を加算します
DATE_FORMAT() 日付を指定された書式に設定します
DATE_SUB() 日付から時間値 (間隔) を引きます
DATEDIFF() 2 つの日付の差を求めます
DAY() DAYOFMONTH() のシノニムです
DAYNAME() 曜日の名前を返します
DAYOFMONTH() 月の日を返します (0 - 31)
DAYOFWEEK() 引数の曜日インデックスを返します
DAYOFYEAR() 年の日を返します (1 - 366)
EXTRACT() 日付の一部を抽出します
FROM_DAYS() 日数を日付に変換します
FROM_UNIXTIME() UNIX タイムスタンプを日付として書式設定します
GET_FORMAT() 日付書式文字列を返します
HOUR() 時を抽出します
LAST_DAY 引数の月の最終日を返します
LOCALTIME(), LOCALTIME NOW() のシノニムです
LOCALTIMESTAMP, LOCALTIMESTAMP() NOW() のシノニムです
MAKEDATE() 年と年間通算日から日付を作成します
MAKETIME() 時、分、秒から時間を作成します
MICROSECOND() 引数からマイクロ秒を返します
MINUTE() 引数から分を返します
MONTH() 渡された日付から月を返します
MONTHNAME() 月の名前を返します
NOW() 現在の日付と時間を返します
PERIOD_ADD() 年月に期間を加算します
PERIOD_DIFF() 期間内の月数を返します
QUARTER() 日付引数から四半期を返します
SEC_TO_TIME() 秒を「HH:MM:SS」形式に変換します
SECOND() 秒 (0-59) を返します
STR_TO_DATE() 文字列を日付に変換します
SUBDATE() 3 つの引数で呼び出されるときは DATE_SUB() のシノニムです
SUBTIME() 時間の差を求めます
SYSDATE() この関数が実行される時間を返します
TIME() 渡された式の時部分を抽出します
TIME_FORMAT() 時間として書式設定します
TIME_TO_SEC() 秒に変換された引数を返します
TIMEDIFF() 時間の差を求めます
TIMESTAMP() 引数が 1 つの場合、この関数は日付または日付時間式を返します。引数が 2 つの場合、引数の合計を返します
TIMESTAMPADD() 日付時間式に間隔を加算します
TIMESTAMPDIFF() 日付時間式から間隔を減算します
TO_DAYS() 日に変換された日付引数を返します
TO_SECONDS() 0 年以降の秒数に変換された日付または日付時間引数を返します
UNIX_TIMESTAMP() UNIX タイムスタンプを返します
UTC_DATE() 現在の UTC 日付を返します
UTC_TIME() 現在の UTC 時間を返します
UTC_TIMESTAMP() 現在の UTC 日付と時間を返します
WEEK() 週番号を返します
WEEKDAY() 曜日インデックスを返します
WEEKOFYEAR() 日付の暦週を返します (0 - 53)
YEAR() 年を返します
YEARWEEK() 年と週を返します

次に、日付関数の使用例を示します。次のクエリーは、過去 30 日以内の date_col 値を含むすべての行を選択します。

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

このクエリーは、将来の日付を持つ行も選択します。

通常、日付値が要求される関数では、日付時間値が受け入れられ、時間の部分は無視されます。通常、時間値が要求される関数では、日付時間値が受け入れられ、日付の部分は無視されます。

現在の日付または時間をそれぞれ返す関数は、クエリー実行の開始時にクエリーごとに 1 回だけ評価されます。つまり、NOW() などの関数が単一クエリー内で複数回参照されても、常に同じ結果が生成されます。(設計上、単一クエリーにはストアドプログラム (ストアドルーチン、トリガー、またはイベント) の呼び出し、およびそのプログラムによって呼び出されるすべてのサブプログラムも含まれています。)この原則は、CURDATE()CURTIME()UTC_DATE()UTC_TIME()UTC_TIMESTAMP()、およびそれらのシノニムにも適用されます。

CURRENT_TIMESTAMP()CURRENT_TIME()CURRENT_DATE()、および FROM_UNIXTIME() 関数は、time_zone システム環境変数の値として使用できる接続の現在のタイムゾーンで値を返します。さらに、UNIX_TIMESTAMP() では、その引数が現在のタイムゾーンでの日付時間値であるとみなされます。セクション10.6「MySQL Server でのタイムゾーンのサポート」を参照してください。

zero 日付または '2001-11-00' のような不完全な日付とともに使用できる日付関数もありますが、使用できない日付関数もあります。通常、日付の一部を抽出する関数は不完全な日付でも正しく機能するため、ゼロ以外の値が要求される場合に 0 を返すことができます。例:

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

その他の関数では完全な日付が要求され、日付が不完全な場合は NULL が返されます。これらには、日付演算を実行する関数や日付の一部を名前にマップする関数が含まれます。例:

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

MySQL 5.6.4 の時点では、いくつかの関数は引数として DATE() 関数の値を渡す際により厳密になったため、ゼロの日付部分を持つ不完全な日付は拒否されます。CONVERT_TZ()DATE_ADD()DATE_SUB()DAYOFYEAR()LAST_DAY()TIMESTAMPDIFF()TO_DAYS()TO_SECONDS()WEEK()WEEKDAY()WEEKOFYEAR()YEARWEEK() 関数が影響を受けます。5.6.5 の LAST_DAY() では、この制限は緩やかで、ゼロの日付部分は許可されていました。

MySQL 5.6.4 以上では、マイクロ秒までの精度を持つ小数秒が TIMEDATETIME、および TIMESTAMP 値でサポートされています。時間引数を取る関数は、小数秒を含む値を受け入れます。時間関数からの戻り値には、必要に応じて小数秒が含まれます。

  • ADDDATE(date,INTERVAL expr unit)ADDDATE(expr,days)

    INTERVAL 形式の 2 番目の引数を付けて呼び出されると、ADDDATE()DATE_ADD() のシノニムになります。関連する関数 SUBDATE()DATE_SUB() のシノニムです。INTERVAL unit 引数については、DATE_ADD() の説明を参照してください。

    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'
    

    days 形式の 2 番目の引数を付けて呼び出されると、MySQL では expr に加算される整数の日数として処理されます。

    mysql> SELECT ADDDATE('2008-01-02', 31);
            -> '2008-02-02'
    
  • ADDTIME(expr1,expr2)

    ADDTIME()expr2expr1 を加算し、その結果を返します。expr1 は時間または日付時間式であり、expr2 は時間式です。

    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() は、日付時間値 dtfrom_tz で指定されたタイムゾーンから、to_tz で指定されたタイムゾーンに変換し、結果の値を返します。タイムゾーンは、セクション10.6「MySQL Server でのタイムゾーンのサポート」で説明されているように指定されます。引数が無効な場合、この関数は NULL を返します。

    from_tz から UTC に変換される際に、値が TIMESTAMP でサポートされている範囲から外れている場合は、変換が実行されません。TIMESTAMP の範囲については、セクション11.1.2「日付と時間型の概要」で説明されています。

    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'
    
    注記

    名前付きタイムゾーン ('MET' または 'Europe/Moscow' など) を使用するには、タイムゾーンテーブルが正しく設定されている必要があります。手順については、セクション10.6「MySQL Server でのタイムゾーンのサポート」を参照してください。

  • CURDATE()

    関数が文字列と数値コンテキストのどちらで使用されているのかに応じて、現在の日付を 'YYYY-MM-DD' または YYYYMMDD 書式の値として返します。

    mysql> SELECT CURDATE();
            -> '2008-06-13'
    mysql> SELECT CURDATE() + 0;
            -> 20080613
    
  • CURRENT_DATECURRENT_DATE()

    CURRENT_DATE および CURRENT_DATE()CURDATE() のシノニムです。

  • CURRENT_TIMECURRENT_TIME([fsp])

    CURRENT_TIME および CURRENT_TIME()CURTIME() のシノニムです。

  • CURRENT_TIMESTAMPCURRENT_TIMESTAMP([fsp])

    CURRENT_TIMESTAMP および CURRENT_TIMESTAMP()NOW() のシノニムです。

  • CURTIME([fsp])

    関数が文字列と数値コンテキストのどちらで使用されているのかに応じて、現在の時間を 'HH:MM:SS' または HHMMSS 書式の値で返します。値は、現在のタイムゾーンで表現されています。

    MySQL 5.6.4 の時点では、0 から 6 までの小数秒の精度を指定するために fsp 引数が指定されている場合は、その桁数の小数秒部分が戻り値に含まれます。5.6.4 よりも前では、すべての引数が無視されます。

    mysql> SELECT CURTIME();
            -> '23:50:26'
    mysql> SELECT CURTIME() + 0;
            -> 235026.000000
    
  • DATE(expr)

    日付または日付時間式 expr の日付部分を抽出します。

    mysql> SELECT DATE('2003-12-31 01:02:03');
            -> '2003-12-31'
    
  • DATEDIFF(expr1,expr2)

    DATEDIFF() は、ある日付から別の日付までの日数の値として表現された expr1expr2 を返します。expr1 および expr2 は、日付または日付時間式です。値の日付部分のみが計算に使用されます。

    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)

    これらの関数は日付演算を実行します。date 引数は、開始日付値または開始日付時間値を指定します。expr は、開始日付から加算または減算される間隔値を指定する式です。expr は文字列であり、負の間隔の場合は - で始めることができます。unit は、式を解釈する際の単位を示すキーワードです。

    INTERVAL キーワードおよび unit 指定子では、大文字と小文字が区別されません。

    次の表には、unit 値ごとに要求される形式の expr 引数を表示します。

    unit 要求される expr 書式
    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'

    戻り値は引数によって異なります。

    • 第 1 引数が DATETIME (または TIMESTAMP) 値である場合と、第 1 引数が DATE で、unit 値に HOURSMINUTES、または SECONDS が使用されている場合は、DATETIME です。

    • それ以外の場合は文字列です。

    必ず結果が DATETIME になるようにするには、CAST() を使用すれば、第 1 引数を DATETIME に変換できます。

    MySQL では、expr 書式の句読点区切り文字が許可されます。表には、提案される区切り文字を表示します。date 引数が DATE 値であり、計算に YEARMONTH、および DAY 部分のみが含まれる (つまり、時間部分は含まれない) 場合は、結果が DATE 値になります。その他の場合は、結果が DATETIME 値になります。

    また、日付演算は、+ または - 演算子とともに INTERVAL を使用して実行することもできます。

    date + INTERVAL expr unit
    date - INTERVAL expr unit
    

    INTERVAL expr unit は、他方の側の式が日付または日付間値である場合に、+ 演算子の一方の側で許可されます。- 演算子では、間隔から日付または日付間値を抽出しても意味がないため、INTERVAL expr unit は右側でのみ許可されます。

    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'
    

    指定した間隔値 (unit キーワードから要求されるすべての間隔部分は含まれません) が短すぎる場合は、MySQL では間隔値の左端部分が省略されているとみなされます。たとえば、DAY_SECONDunit を指定した場合は、expr の値には日、時間、分、秒の部分が含まれるとみなされます。'1:10' のような値を指定すると、MySQL では日と時間の部分が欠落していて、値は分と秒を表しているとみなされます。つまり、'1:10' DAY_SECOND は、'1:10' MINUTE_SECOND と同等の方法で解釈されます。これは、MySQL で TIME 値が時間ではなく経過時間を表していると解釈される方法に類似しています。

    expr は文字列として処理されるため、INTERVAL に文字列以外の値を指定する場合は注意してください。たとえば、間隔指定子が HOUR_MINUTE の場合は、6/41.5000 に評価され、1 時間 5000 分として処理されます。

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

    間隔値が予想どおりに解釈されるようにするには、CAST() 演算を使用します。6/4 を 1 時間 5 分として処理するには、小数点以下の桁数が 1 桁の DECIMAL 値にキャストします。

    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'
    

    時間部分が含まれるものを日付値に加算したり、日付値から減算したりすると、自動的に結果が日付時間値に変換されます。

    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'
    

    MONTHYEAR_MONTH、または YEAR を加算した結果の日付に、新しい月の最大日数よりも大きな日が含まれる場合は、その日が新しい月の最大日数に調整されます。

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

    日付算術演算では、完全な日付が必須であるため、'2006-07-00' のような不完全な日付や、誤った形式の日付では正常に機能しません。

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

    format 文字列に従って、date 値を書式設定します。

    次の指定子が format 文字列で使用されている場合があります。書式指定子文字の前には、% 文字を付ける必要があります。

    指定子 説明
    %a 簡略曜日名 (Sun..Sat)
    %b 簡略月名 (Jan..Dec)
    %c 月、数字 (0..12)
    %D 英語のサフィクスを持つ日付 (0th, 1st, 2nd, 3rd, …)
    %d 日、数字 (00..31)
    %e 日、数字 (0..31)
    %f マイクロ秒 (000000..999999)
    %H 時間 (00..23)
    %h 時間 (01..12)
    %I 時間 (01..12)
    %i 分、数字 (00..59)
    %j 年間通算日 (001..366)
    %k 時 (0..23)
    %l 時 (1..12)
    %M 月名 (January..December)
    %m 月、数字 (00..12)
    %p AM または PM
    %r 時間、12 時間単位 (hh:mm:ssAM または PM が続く)
    %S 秒 (00..59)
    %s 秒 (00..59)
    %T 時間、24 時間単位 (hh:mm:ss)
    %U 週 (00..53)、日曜日が週の初日、WEEK() モード 0
    %u 週 (00..53)、月曜日が週の初日、WEEK() モード 1
    %V 週 (01..53)、日曜日が週の初日、WEEK() モード 2、%X とともに使用
    %v 週 (01..53)、月曜日が週の初日、WEEK() モード 3、%x とともに使用
    %W 曜日名 (Sunday..Saturday)
    %w 曜日 (0=Sunday..6=Saturday)
    %X 年間の週、日曜日が週の初日、数字、4 桁、%V とともに使用
    %x 年間の週、月曜日が週の初日、数字、4 桁、%v とともに使用
    %Y 年、数字、4 桁
    %y 年、数字 (2 桁)
    %% リテラル % 文字
    %x x (上記にないすべての x)

    MySQL では '2014-00-00' などの不完全な日付の格納が許可されるため、月および日の指定子の範囲はゼロから始まります。

    日および月の名前と略語に使用される言語は、lc_time_names システム変数 (セクション10.7「MySQL Server のロケールサポート」) の値で制御されます。

    %U%u%V、および %v 指定子のモード値については、WEEK() 関数の説明を参照してください。モードによって、週番号が付与される方法が影響を受けます。

    DATE_FORMAT() は、ASCII 以外の文字を含む月および週の名前を返すことができるように、character_set_connection および collation_connection で指定された文字セットおよび照合順序を含む文字列を返します。

    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)

    DATE_ADD() の説明を参照してください。

  • DAY(date)

    DAY()DAYOFMONTH() のシノニムです。

  • DAYNAME(date)

    date に対応する曜日の名前を返します。名前に使用される言語は、lc_time_names システム変数 (セクション10.7「MySQL Server のロケールサポート」) の値で制御されます。

    mysql> SELECT DAYNAME('2007-02-03');
            -> 'Saturday'
    
  • DAYOFMONTH(date)

    1 から 31 までの範囲内で date に対応する日を返します。'0000-00-00''2008-00-00' のように日の部分がゼロの場合は、0 を返します。

    mysql> SELECT DAYOFMONTH('2007-02-03');
            -> 3
    
  • DAYOFWEEK(date)

    date の曜日インデックス (1 = Sunday、2 = Monday、…、7 = Saturday) を返します。これらのインデックス値は、ODBC 標準に対応しています。

    mysql> SELECT DAYOFWEEK('2007-02-03');
            -> 7
    
  • DAYOFYEAR(date)

    1 から 366 までの範囲内で date に対応する通日を返します。

    mysql> SELECT DAYOFYEAR('2007-02-03');
            -> 34
    
  • EXTRACT(unit FROM date)

    EXTRACT() 関数では、DATE_ADD() または DATE_SUB() と同じ単位指定子が使用されますが、データ演算が実行されるのではなく、データから一部が抽出されます。

    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)

    日数 N が指定され、DATE 値を返します。

    mysql> SELECT FROM_DAYS(730669);
            -> '2007-07-03'
    

    古い日付では、FROM_DAYS() を慎重に使用してください。グレゴリオ暦 (1582) の出現よりも前の値とともに使用することを目的に設計されていません。セクション12.8「MySQL で使用されるカレンダー」を参照してください。

  • FROM_UNIXTIME(unix_timestamp), FROM_UNIXTIME(unix_timestamp,format)

    関数が文字列と数値のどちらのコンテキストで使用されたのかに応じて、unix_timestamp 引数の表現を 'YYYY-MM-DD HH:MM:SS' または YYYYMMDDHHMMSS 書式の値として返します。値は、現在のタイムゾーンで表現されています。unix_timestamp は、UNIX_TIMESTAMP() 関数で生成されるような内部タイムスタンプ値です。

    format が指定されている場合は、DATE_FORMAT() 関数のエントリで一覧表示される場合と同じ方法で使用される format 文字列に従って、結果が書式設定されます。

    mysql> SELECT FROM_UNIXTIME(1196440219);
            -> '2007-11-30 10:30:19'
    mysql> SELECT FROM_UNIXTIME(1196440219) + 0;
            -> 20071130103019.000000
    mysql> SELECT FROM_UNIXTIME(UNIX_TIMESTAMP(),
        ->                      '%Y %D %M %h:%i:%s %x');
            -> '2007 30th November 10:30:59 2007'
    

    注: UNIX_TIMESTAMP() および FROM_UNIXTIME() を使用して TIMESTAMP 値と Unix タイムスタンプ値とを変換する場合は、どちらの方向でもマッピングが 1 対 1 ではないため、変換は不可逆です。詳細は UNIX_TIMESTAMP() 関数の説明を参照してください。

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

    書式文字列を返します。この関数は、DATE_FORMAT() およびSTR_TO_DATE() 関数と組み合わせて使用すると便利です。

    1 番目と 2 番目の引数に値を指定できるため、複数の書式文字列を生成できます (使用される指定子については、DATE_FORMAT() 関数の説明で示す表を参照してください)。ISO 書式は ISO 8601 ではなく、ISO 9075 を参照しています。

    関数呼び出し 結果
    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 は、GET_FORMAT() への 1 番目の引数としても使用できます。その場合、関数は DATETIME の場合と同じ値を返します。

    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)

    time に対応する時を返します。戻り値の範囲は、日付時間値の 0 から 23 までです。ただし、TIME 値の範囲は実際にはもっと大きいため、HOUR23 よりも大きい値を返すことができます。

    mysql> SELECT HOUR('10:05:03');
            -> 10
    mysql> SELECT HOUR('272:59:59');
            -> 272
    
  • LAST_DAY(date)

    日付または日付時間の値が指定され、月の最終日に対応する値を返します。引数が無効である場合は、NULL を返します。

    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 および LOCALTIME()NOW() のシノニムです。

  • LOCALTIMESTAMP, LOCALTIMESTAMP([fsp])

    LOCALTIMESTAMP および LOCALTIMESTAMP()NOW() のシノニムです。

  • MAKEDATE(year,dayofyear)

    指定された年と年間通算値から、日付を返します。dayofyear は 0 よりも大きくする必要があり、それ以外の場合は結果が NULL になります。

    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)

    hourminute、および second 引数から計算された時間値を返します。

    MySQL 5.6.4 の時点では、second 引数に小数部を含めることができます。

    mysql> SELECT MAKETIME(12,15,30);
            -> '12:15:30'
    
  • MICROSECOND(expr)

    0 から 999999 までの範囲内の数値として、時間または日付時間式 expr からのマイクロ秒を返します。

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

    0 から 59 までの範囲内で、time に対応する分を返します。

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

    1 (1 月) から 12 (12 月) の範囲内で、date に対応する月を返します。'0000-00-00''2008-00-00' のように月の部分がゼロの場合は、0 を返します。

    mysql> SELECT MONTH('2008-02-03');
            -> 2
    
  • MONTHNAME(date)

    date に対応する月の完全名を返します。名前に使用される言語は、lc_time_names システム変数 (セクション10.7「MySQL Server のロケールサポート」) の値で制御されます。

    mysql> SELECT MONTHNAME('2008-02-03');
            -> 'February'
    
  • NOW([fsp])

    関数が文字列と数値のどちらのコンテキストで使用されているのかに応じて、現在の日付と時間を 'YYYY-MM-DD HH:MM:SS' または YYYYMMDDHHMMSS 書式の値として返します。値は、現在のタイムゾーンで表現されています。

    MySQL 5.6.4 の時点では、0 から 6 までの小数秒の精度を指定するために fsp 引数が指定されている場合は、その桁数の小数秒部分が戻り値に含まれます。5.6.4 よりも前では、すべての引数が無視されます。

    mysql> SELECT NOW();
            -> '2007-12-15 23:50:26'
    mysql> SELECT NOW() + 0;
            -> 20071215235026.000000
    

    NOW() は、ステートメントが実行を開始する時刻を示す定数時間を返します。(ストアドファンクションまたはトリガーでは、NOW() は関数またはトリガーステートメントが実行を開始する時間を返します。)これは、正確な実行時間を返す SYSDATE() の動作とは異なります。

    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 |
    +---------------------+----------+---------------------+
    

    さらに、SET TIMESTAMP ステートメントによって、NOW() で返された値は影響を受けますが、SYSDATE() で返された値は影響を受けません。つまり、バイナリログのタイムスタンプ設定は、SYSDATE() の呼び出しに影響しないことを意味します。タイムスタンプをゼロ以外の値に設定すると、後続の NOW() が起動されるたびに、その値が返されます。タイムスタンプをゼロに設定すると、この効果が取り消され、再度 NOW() が現在の日付と時間を返すようになります。

    2 つの関数の相違点についての詳細は、SYSDATE() の説明を参照してください。

  • PERIOD_ADD(P,N)

    N 月を期間 P に (YYMM または YYYYMM の書式で) 加算します。YYYYMM の書式で値を返します。

    注記

    期間引数 P は、日付値ではありません

    mysql> SELECT PERIOD_ADD(200801,2);
            -> 200803
    
  • PERIOD_DIFF(P1,P2)

    期間 P1P2 間の月数を返します。P1 および P2 は、YYMM または YYYYMM の書式にする必要があります。期間引数 P1 および P2 は日付値ではないことに注意してください。

    mysql> SELECT PERIOD_DIFF(200802,200703);
            -> 11
    
  • QUARTER(date)

    1 から 4 までの範囲内で date に対応する四半期を返します。

    mysql> SELECT QUARTER('2008-04-01');
            -> 2
    
  • SECOND(time)

    0 から 59 までの範囲内で、time に対応する秒数を返します。

    mysql> SELECT SECOND('10:05:03');
            -> 3
    
  • SEC_TO_TIME(seconds)

    TIME 値として、時、分、秒に変換された seconds 引数を返します。結果の範囲は、TIME データ型の範囲に制約されます。引数がその範囲外の値に対応している場合は、警告が発行されます。

    mysql> SELECT SEC_TO_TIME(2378);
            -> '00:39:38'
    mysql> SELECT SEC_TO_TIME(2378) + 0;
            -> 3938
    
  • STR_TO_DATE(str,format)

    これは DATE_FORMAT() 関数の逆です。文字列 str と書式文字列 format が指定されます。STR_TO_DATE() は、書式文字列に日付と時間の両方の部分が含まれる場合は DATETIME 値を返し、文字列に日付と時間の部分の一方のみが含まれる場合は DATE または TIME 値を返します。str から抽出された日付値、時間値、または日付時間値が不正な場合は、STR_TO_DATE() によって NULL が返され、警告が発行されます。

    サーバーは str をスキャンすることで、format の一致を試みます。書式文字列には、リテラル文字と % で始まる書式指定子を含めることができます。format 内のリテラル文字は、str 内と完全に一致する必要があります。format 内の書式指定子は、str 内の日付または時間の部分に一致する必要があります。format で使用できる指定子については、DATE_FORMAT() 関数の説明を参照してください。

    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'
    

    str の先頭からスキャンが開始され、一致しない format が見つかった場合は失敗します。str の末尾にある余分な文字は、無視されます。

    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'
    

    指定されていない日付または時間の部分の値は 0 になるため、str に指定された値が不完全な場合は、結果の一部または全部が 0 に設定されます。

    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'
    

    日付値の部分をチェックする範囲は、セクション11.3.1「DATE、DATETIME、および TIMESTAMP 型」の説明どおりです。たとえば、ゼロの日付または部分値が 0 の日付は、このような値が許可されないように SQL モードが設定されていなければ、許可されます。

    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'
    
    注記

    週が月の境界を越えた場合は、年と週の組み合わせでは年と月を一意に識別できないため、"%X%V" の書式を使用しても、年と週の文字列を日付に変換できません。年と週を日付に変換するには、曜日も指定する必要があります。

    mysql> SELECT STR_TO_DATE('200442 Monday', '%X%V %W');
            -> '2004-10-18'
    
  • SUBDATE(date,INTERVAL expr unit), SUBDATE(expr,days)

    INTERVAL 形式で 2 番目の引数を付けて呼び出されると、SUBDATE()DATE_SUB() のシノニムになります。INTERVAL unit 引数については、DATE_ADD() の説明を参照してください。

    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'
    

    2 番目の形式では、days の整数値を使用できます。このような場合は、日付または日付時間式 expr から日数が減算されると解釈されます。

    mysql> SELECT SUBDATE('2008-01-02 12:00:00', 31);
            -> '2007-12-02 12:00:00'
    
  • SUBTIME(expr1,expr2)

    SUBTIME() は、expr1 と同じ書式で表現される expr1expr2 を返します。expr1 は時間または日付時間式であり、expr2 は時間式です。

    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])

    関数が文字列と数値のどちらのコンテキストで使用されているのかに応じて、現在の日付と時間を 'YYYY-MM-DD HH:MM:SS' または YYYYMMDDHHMMSS 書式の値として返します。

    MySQL 5.6.4 の時点では、0 から 6 までの小数秒の精度を指定するために fsp 引数が指定されている場合は、その桁数の小数秒部分が戻り値に含まれます。5.6.4 よりも前では、すべての引数が無視されます。

    SYSDATE() は、実行された時間を返します。これは、ステートメントが実行を開始する時間を示す定数時間を返す NOW() の動作とは異なります。(ストアドファンクションまたはトリガーでは、NOW() は関数またはトリガーステートメントが実行を開始する時間を返します。)

    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 |
    +---------------------+----------+---------------------+
    

    さらに、SET TIMESTAMP ステートメントによって、NOW() で返された値は影響を受けますが、SYSDATE() で返された値は影響を受けません。つまり、バイナリログのタイムスタンプ設定は、SYSDATE() の呼び出しに影響しないことを意味します。

    SYSDATE() は、同じステートメント内でもさまざまな値を返すことができ、SET TIMESTAMP による影響も受けないため、非決定的です。そのため、ステートメントベースのバイナリロギングが使用されている場合は、レプリケーションで安全に使用できません。これが問題となる場合は、行ベースのロギングを使用できます。

    また、--sysdate-is-now オプションを使用すると、SYSDATE()NOW() のエイリアスにすることができます。これは、オプションがマスターとスレーブの両方で使用される場合に機能します。

    SYSDATE() に非決定的な特性があるということは、それを参照する式を評価する際にインデックスを使用できないことも意味します。

  • TIME(expr)

    時間または日付時間式 expr の時部分を抽出し、文字列として返します。

    この関数は、ステートメントベースのレプリケーションでは安全に使用できません。binlog_formatSTATEMENT に設定されているときに、この関数を使用すると、警告のログが記録されます。

    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() は、時間値として表現された expr1expr2 を返します。expr1 および expr2 は時間または日付時間式ですが、両方とも同じ型にする必要があります。

    TIMEDIFF() で返される結果は、TIME 値で許可される範囲に制限されています。また、TIMESTAMPDIFF() および UNIX_TIMESTAMP() 関数のいずれかを使用することもできます。両方とも整数を返します。

    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)

    引数を 1 つ付けると、この関数は日付または日付時間式 expr を日付時間値として返します。引数を 2 つ付けると、時間式 expr2 を日付または日付時間式 expr1 に加算し、その結果を日付時間値として返します。

    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)

    整数式 interval を日付または日付時間式 datetime_expr に加算します。interval の単位は、unit 引数で指定されます。この引数は、MICROSECOND (マイクロ秒)、SECONDMINUTEHOURDAYWEEKMONTHQUARTERYEAR 値のいずれかにする必要があります。

    unit 値を指定するには、ここで示したキーワードのいずれかを使用するか、SQL_TSI_ をプリフィクスとして付けます。たとえば、DAYSQL_TSI_DAY は両方とも有効です。

    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)

    datetime_expr2datetime_expr1 を返します。datetime_expr1datetime_expr2 は、日付または日付時間式です。式の一方が日付で、他方が日付時間にすることもできます。日付値は、必要に応じて時間部分が '00:00:00' の日付時間として処理されます。結果 (整数) の単位は、unit 引数で指定されます。unit の有効な値は、TIMESTAMPADD() 関数の説明で一覧表示された値と同じです。

    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
    
    注記

    この関数の日付または日付時間引数の順序は、TIMESTAMP() 関数を 2 つの引数を指定して呼び出す場合の順序と逆になります。

  • TIME_FORMAT(time,format)

    これは DATE_FORMAT() 関数と同様に使用されますが、format 文字列には時間、分、秒、マイクロ秒の書式指定子のみを含めることができます。その他の指定子では、NULL 値または 0 が生成されます。

    time 値に 23 よりも大きな時間部分が含まれる場合は、%H および %k 時間書式指定子によって、0..23 の通常の範囲よりも大きな値が生成されます。その他の時間書式指定子では、時間値モジュロ 12 が生成されます。

    mysql> SELECT TIME_FORMAT('100:00:00', '%H %k %h %I %l');
            -> '100 100 04 04 4'
    
  • TIME_TO_SEC(time)

    秒に変換された time 引数を返します。

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

    日付 date が指定され、日数 (0 年以降の日数) を返します。

    mysql> SELECT TO_DAYS(950501);
            -> 728779
    mysql> SELECT TO_DAYS('2007-10-07');
            -> 733321
    

    TO_DAYS() は、カレンダーが変更された際に失われた日が考慮されないため、グレゴリオ暦 (1582) の出現よりも前の値とともに使用するために設計されていません。日付が 1582 よりも前の場合は (ほかのロケールでは、さらにあとの年になる可能性があります)、この関数の結果は信頼できません。詳細は セクション12.8「MySQL で使用されるカレンダー」を参照してください。

    MySQL では セクション11.3「日付と時間型」 のルールを使用して、日付の 2 桁の年の値が 4 桁の形式に変換されることを忘れないでください。たとえば、'2008-10-07''08-10-07' は同じ日付と認識されます。

    mysql> SELECT TO_DAYS('2008-10-07'), TO_DAYS('08-10-07');
            -> 733687, 733687
    

    MySQL では、ゼロの日付は '0000-00-00' として定義されます。ただし、このデータ自体は無効とみなされます。つまり、'0000-00-00' および '0000-01-01' の場合、TO_DAYS() は次に示す値を返します。

    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)
    

    このことは、ALLOW_INVALID_DATES SQL サーバーモードが有効であるかどうかに関係なく当てはまります。

  • TO_SECONDS(expr)

    日付または日付時間の expr が指定され、0 年以降の日数を返します。expr が有効な日付または日付時間の値ではない場合は、NULL を返します。

    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
    

    TO_DAYS() と同様に、TO_SECONDS() は、カレンダーが変更された際に失われた日が考慮されないため、グレゴリオ暦 (1582) の出現よりも前の値とともに使用する目的で設計されていません。日付が 1582 よりも前の場合は (ほかのロケールでは、さらにあとの年になる可能性があります)、この関数の結果は信頼できません。詳細は セクション12.8「MySQL で使用されるカレンダー」を参照してください。

    TO_DAYS() と同様に、TO_SECONDS()セクション11.3「日付と時間型」 のルールを使用して日付の 2 桁の年の値を 4 桁の形式に変換します。

    MySQL では、ゼロの日付は '0000-00-00' として定義されます。ただし、このデータ自体は無効とみなされます。つまり、'0000-00-00' および '0000-01-01' の場合、TO_SECONDS() は次に示す値を返します。

    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)
    

    このことは、ALLOW_INVALID_DATES SQL サーバーモードが有効であるかどうかに関係なく当てはまります。

  • UNIX_TIMESTAMP()UNIX_TIMESTAMP(date)

    引数なしで呼び出された場合は、Unix タイムスタンプ ('1970-01-01 00:00:00' UTC 以降の秒数) を符号なし整数として返します。date 引数を付けて UNIX_TIMESTAMP() が呼び出された場合は、その引数の値が '1970-01-01 00:00:00' UTC 以降の秒数として返されます。date には、DATE 文字列、DATETIME 文字列、TIMESTAMPYYMMDD または YYYYMMDD 書式の数値を指定できます。サーバーは date を現在のタイムゾーンの値として解釈し、UTC の内部値に変換します。クライアントは、セクション10.6「MySQL Server でのタイムゾーンのサポート」で説明するとおりに、独自のタイムゾーンを設定できます。

    mysql> SELECT UNIX_TIMESTAMP();
            -> 1196440210
    mysql> SELECT UNIX_TIMESTAMP('2007-11-30 10:30:19');
            -> 1196440219
    

    UNIX_TIMESTAMP()TIMESTAMP カラムで使用されると、暗黙的に string-to-Unix-timestamp に変換されずに、内部タイムスタンプ値が直接返されます。UNIX_TIMESTAMP() に範囲外の日付を渡すと、0 が返されます。

    注: UNIX_TIMESTAMP() および FROM_UNIXTIME() を使用して TIMESTAMP 値と Unix タイムスタンプ値とを変換する場合は、どちらの方向でもマッピングが 1 対 1 ではないため、変換は不可逆です。たとえば、ローカルタイムゾーンを変更するための変換が原因で、2 つの UNIX_TIMESTAMP() で 2 つの TIMESTAMP 値が同じ Unix タイムスタンプ値にマップされる可能性があります。FROM_UNIXTIME() は、その値を元の TIMESTAMP 値のいずれかにのみマップし直します。次に、CET タイムゾーンでの TIMESTAMP 値の使用例を示します。

    
    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       |
    +---------------------------+
    

    UNIX_TIMESTAMP() カラムを減算する場合は、結果を符号付きの整数にキャストします。セクション12.10「キャスト関数と演算子」を参照してください。

  • UTC_DATEUTC_DATE()

    関数が文字列と数値のどちらのコンテキストで使用されているのかに応じて、現在の UTC 日付を 'YYYY-MM-DD' または YYYYMMDD 書式の値で返します。

    mysql> SELECT UTC_DATE(), UTC_DATE() + 0;
            -> '2003-08-14', 20030814
    
  • UTC_TIME, UTC_TIME([fsp])

    関数が文字列と数値のどちらのコンテキストで使用されているのかに応じて、現在の UTC 時間を 'HH:MM:SS' または HHMMSS 書式の値で返します。

    MySQL 5.6.4 の時点では、0 から 6 までの小数秒の精度を指定するために fsp 引数が指定されている場合は、その桁数の小数秒部分が戻り値に含まれます。5.6.4 よりも前では、すべての引数が無視されます。

    mysql> SELECT UTC_TIME(), UTC_TIME() + 0;
            -> '18:07:53', 180753.000000
    
  • UTC_TIMESTAMPUTC_TIMESTAMP([fsp])

    関数が文字列と数値のどちらのコンテキストで使用されているのかに応じて、現在の UTC 日付と時間を 'YYYY-MM-DD HH:MM:SS' または YYYYMMDDHHMMSS 書式の値として返します。

    MySQL 5.6.4 の時点では、0 から 6 までの小数秒の精度を指定するために fsp 引数が指定されている場合は、その桁数の小数秒部分が戻り値に含まれます。5.6.4 よりも前では、すべての引数が無視されます。

    mysql> SELECT UTC_TIMESTAMP(), UTC_TIMESTAMP() + 0;
            -> '2003-08-14 18:08:04', 20030814180804.000000
    
  • WEEK(date[,mode])

    この関数は、date に対応する週番号を返します。2 つの引数を取る形式の WEEK() を使用すると、週が日曜日と月曜日のどちらから始まるのか、および戻り値が 0 から 53までと 1 から 53 までのどちらの範囲内であるのかを指定できます。mode 引数が省略された場合は、default_week_format システム変数の値が使用されます。セクション5.1.4「サーバーシステム変数」を参照してください。

    次の表では、mode 引数がどのように機能するのかについて説明します。

    モード 週の 1 日目 範囲 第 1 週は次の条件を満たす最初の週
    0 日曜日 0-53 本年の日曜日を含む
    1 月曜日 0-53 本年の 4 日以上を含む
    2 日曜日 1-53 本年の日曜日を含む
    3 月曜日 1-53 本年の 4 日以上を含む
    4 日曜日 0-53 本年の 4 日以上を含む
    5 月曜日 0-53 本年の月曜日を含む
    6 日曜日 1-53 本年の 4 日以上を含む
    7 月曜日 1-53 本年の月曜日を含む

    本年の 4 日以上を含むという意味を持つ mode 値では、ISO 8601:1988 に従って週番が付けられます。

    • 1 月 1 日を含む週に新年の 4 日以上が含まれる場合は、その週が第 1 週です。

    • それ以外の場合は、前年の最終週となり、次の週が第 1 週です。

    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
    

    日付が前年の最終週に入っている場合は、オプションの mode 引数として236、または 7 を使用しなければ、MySQL によって 0 が返されます。

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

    指定された日付は実際には 1999 年の第 52 週に発生するため、WEEK()52 を返す必要があると議論されることもあります。代わりに WEEK() は、戻り値が指定された年の週番号となるように 0 を返します。これにより、日付から日付部分を抽出するその他の関数と組み合わせると、WEEK() 関数を信頼して使用できるようになります。

    指定された日付に対応する週の 1 日目を含む年について評価された結果を優先する場合は、オプションの mode 引数として 025、または 7 を使用します。

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

    または、YEARWEEK() 関数を使用します。

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

    date に対応する曜日インデックス (0 = Monday、1 = Tuesday、…6 = Sunday) を返します。

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

    1 から 53 までの範囲内で、日付の暦週を返します。WEEKOFYEAR()WEEK(date,3) に同等の互換性のある関数です。

    mysql> SELECT WEEKOFYEAR('2008-02-20');
            -> 8
    
  • YEAR(date)

    1000 から 9999 までの範囲内で、date に対応する年を返します。日付がゼロの場合は、0 を返します。

    mysql> SELECT YEAR('1987-01-01');
            -> 1987
    
  • YEARWEEK(date)YEARWEEK(date,mode)

    日付に対応する年と週を返します。mode 引数は、WEEK() への mode 引数とまったく同様に機能します。結果の年と日付引数の年では、その年の最初と最後の週が異なる可能性があります。

    mysql> SELECT YEARWEEK('1987-01-01');
            -> 198653
    

    WEEK() はその後、指定された年のコンテキストで週を返すため、週番号はオプションの引数 0 または 1 を付けた場合に WEEK() 関数で返される数字 (0) とは異なります。


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)
     "
;
      
$resultmysql_query($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
  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 ;
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