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11.1.2. Overview of Date and Time Types

A summary of the temporal data types follows. For additional information, see Section 11.3, “Date and Time Types”. Type storage requirements are given in Section 11.5, “Data Type Storage Requirements”.

The SUM() and AVG() aggregate functions do not work with temporal values. (They convert the values to numbers, which loses the part after the first non-numeric character.) To work around this problem, you can convert to numeric units, perform the aggregate operation, and convert back to a temporal value. Examples:

SELECT SEC_TO_TIME(SUM(TIME_TO_SEC(time_col))) FROM tbl_name;
SELECT FROM_DAYS(SUM(TO_DAYS(date_col))) FROM tbl_name;
  • DATE

    A date. The supported range is '1000-01-01' to '9999-12-31'. MySQL displays DATE values in 'YYYY-MM-DD' format, but allows you to assign values to DATE columns using either strings or numbers.

  • DATETIME

    A date and time combination. The supported range is '1000-01-01 00:00:00' to '9999-12-31 23:59:59'. MySQL displays DATETIME values in 'YYYY-MM-DD HH:MM:SS' format, but allows you to assign values to DATETIME columns using either strings or numbers.

  • TIMESTAMP[(M)]

    A timestamp. The range is '1970-01-01 00:00:00' to partway through the year 2037.

    A TIMESTAMP column is useful for recording the date and time of an INSERT or UPDATE operation. By default, the first TIMESTAMP column in a table is automatically set to the date and time of the most recent operation if you do not assign it a value yourself. You can also set any TIMESTAMP column to the current date and time by assigning it a NULL value. Variations on automatic initialization and update properties are described in Section 11.3.1.1, “TIMESTAMP Properties as of MySQL 4.1”.

    A TIMESTAMP value is returned as a string in the format 'YYYY-MM-DD HH:MM:SS' whose display width is fixed at 19 characters. To obtain the value as a number, you should add +0 to the timestamp column.

    Note: The TIMESTAMP format that was used prior to MySQL 4.1 is not supported in MySQL 5.1; see MySQL 3.23, 4.0, 4.1 Reference Manual for information regarding the old format.

  • TIME

    A time. The range is '-838:59:59' to '838:59:59'. MySQL displays TIME values in 'HH:MM:SS' format, but allows you to assign values to TIME columns using either strings or numbers.

  • YEAR[(2|4)]

    A year in two-digit or four-digit format. The default is four-digit format. In four-digit format, the allowable values are 1901 to 2155, and 0000. In two-digit format, the allowable values are 70 to 69, representing years from 1970 to 2069. MySQL displays YEAR values in YYYY format, but allows you to assign values to YEAR columns using either strings or numbers.


 
 
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