A summary of the temporal data types follows. For additional information about properties and storage requirements of the temporal types, see Section 11.3, “Date and Time Types”, and Section 11.7, “Data Type Storage Requirements”. For descriptions of functions that operate on temporal values, see Section 12.7, “Date and Time Functions”.
For the DATE and
DATETIME range descriptions,
“supported” means that although earlier values
might work, there is no guarantee.
A date. The supported range is
'1000-01-01' to
'9999-12-31'. MySQL displays
DATE values in
'YYYY-MM-DD' format, but permits
assignment of values to DATE
columns using either strings or numbers.
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 permits
assignment of values to
DATETIME columns using either
strings or numbers.
A timestamp. The range is '1970-01-01
00:00:01' UTC to '2038-01-19
03:14:07' UTC.
TIMESTAMP values are stored
as the number of seconds since the epoch
('1970-01-01 00:00:00' UTC). A
TIMESTAMP cannot represent
the value '1970-01-01 00:00:00' because
that is equivalent to 0 seconds from the epoch and the value
0 is reserved for representing '0000-00-00
00:00:00', the “zero”
TIMESTAMP value.
Unless specified otherwise, the first
TIMESTAMP column in a table
is defined to be automatically set to the date and time of
the most recent modification if not explicitly assigned a
value. This makes TIMESTAMP
useful for recording the timestamp of an
INSERT or
UPDATE operation. You can
also set any TIMESTAMP column
to the current date and time by assigning it a
NULL value, unless it has been defined
with the NULL attribute to permit
NULL values. The automatic initialization
and updating to the current date and time can be specified
using DEFAULT CURRENT_TIMESTAMP and
ON UPDATE CURRENT_TIMESTAMP clauses, as
described in Section 11.3.5, “Automatic Initialization and Updating for TIMESTAMP”.
A time. The range is '-838:59:59' to
'838:59:59'. MySQL displays
TIME values in
'HH:MM:SS' format, but permits assignment
of values to TIME columns
using either strings or numbers.
A year in two-digit or four-digit format. The default is
four-digit format. YEAR(2) or
YEAR(4) differ in display format, but
have the same range of values. In four-digit format, values
display as 1901 to
2155, and 0000. In
two-digit format, values display as 70 to
69, representing years from 1970 to 2069.
MySQL displays YEAR values in
YYYY or YY format, but
permits assignment of values to
YEAR columns using either
strings or numbers.
The YEAR(2) data type has certain
issues that you should consider before choosing to use it.
As of MySQL 5.5.27, YEAR(2) is
deprecated. For more information, see
Section 11.3.4, “YEAR(2) Limitations and Migrating to YEAR(4)”.
For additional information about YEAR
display format and interpretation of input values, see
Section 11.3.3, “The YEAR Type”.
The SUM() and
AVG() aggregate functions do not
work with temporal values. (They convert the values to numbers,
losing everything after the first nonnumeric character.) To work
around this problem, 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))) FROMtbl_name; SELECT FROM_DAYS(SUM(TO_DAYS(date_col))) FROMtbl_name;
The MySQL server can be run with the
MAXDB SQL mode enabled. In
this case, TIMESTAMP is
identical with DATETIME. If
this mode is enabled at the time that a table is created,
TIMESTAMP columns are created
as DATETIME columns. As a
result, such columns use
DATETIME display format, have
the same range of values, and there is no automatic
initialization or updating to the current date and time. See
Section 5.1.8, “Server SQL Modes”.