TIMESTAMP types are related. This section
describes their characteristics, how they are similar, and how
they differ. MySQL recognizes
values in several formats, described in
Section 9.1.3, “Date and Time Literals”. For the
descriptions, “supported” means that although
earlier values might work, there is no guarantee.
DATE type is used for values with a date
part but no time part. MySQL retrieves and displays
DATE values in
format. The supported range is
DATETIME type is used for values that
contain both date and time parts. MySQL retrieves and displays
DATETIME values in
' format. The supported range is
'1000-01-01 00:00:00' to
TIMESTAMP data type is used for values
that contain both date and time parts.
TIMESTAMP has a range of
00:00:01' UTC to
TIMESTAMP values from the
current time zone to UTC for storage, and back from UTC to the
current time zone for retrieval. (This does not occur for other
types such as
DATETIME.) By default, the
current time zone for each connection is the server's time. The
time zone can be set on a per-connection basis. As long as the
time zone setting remains constant, you get back the same value
you store. If you store a
and then change the time zone and retrieve the value, the
retrieved value is different from the value you stored. This
occurs because the same time zone was not used for conversion in
both directions. The current time zone is available as the value
variable. For more information, see
Section 5.1.12, “MySQL Server Time Zone Support”.
TIMESTAMP data type offers automatic
initialization and updating to the current date and time. For
more information, see
Section 11.2.6, “Automatic Initialization and Updating for TIMESTAMP”.
value can include a trailing fractional seconds part in up to
microseconds (6 digits) precision. Although this fractional part
is recognized, it is discarded from values stored into
columns. For information about fractional seconds support in
MySQL, see Section 11.2.7, “Fractional Seconds in Time Values”.
TIMESTAMP values are converted to the
“zero” value of the appropriate type
00:00:00'), if the SQL mode permits this conversion.
The precise behavior depends on which if any of strict SQL mode
NO_ZERO_DATE SQL mode
are enabled; see Section 5.1.10, “Server SQL Modes”.
Be aware of certain properties of date value interpretation in MySQL:
MySQL permits a “relaxed” format for values specified as strings, in which any punctuation character may be used as the delimiter between date parts or time parts. In some cases, this syntax can be deceiving. For example, a value such as
'10:11:12'might look like a time value because of the
:, but is interpreted as the year
'2010-11-12'if used in date context. The value
'10:45:15'is converted to
'45'is not a valid month.
The server requires that month and day values be valid, and not merely in the range 1 to 12 and 1 to 31, respectively. With strict mode disabled, invalid dates such as
'2004-04-31'are converted to
'0000-00-00'and a warning is generated. With strict mode enabled, invalid dates generate an error. To permit such dates, enable
ALLOW_INVALID_DATES. See Section 5.1.10, “Server SQL Modes”, for more information.
MySQL does not accept
TIMESTAMPvalues that include a zero in the day or month column or values that are not a valid date. The sole exception to this rule is the special “zero” value
'0000-00-00 00:00:00', if the SQL mode permits this value. The precise behavior depends on which if any of strict SQL mode and the
NO_ZERO_DATESQL mode are enabled; see Section 5.1.10, “Server SQL Modes”.
Dates containing 2-digit year values are ambiguous because the century is unknown. MySQL interprets 2-digit year values using these rules:
Year values in the range
Year values in the range
See also Section 11.2.9, “2-Digit Years in Dates”.
The MySQL server can be run with the
MAXDB SQL mode enabled. In
TIMESTAMP is identical with
DATETIME. If this mode is enabled at the
time that a table is created,
columns are created as
DATETIME columns. As
a result, such columns use
format, have the same range of values, and there is no
automatic initialization or updating to the current date and
time. See Section 5.1.10, “Server SQL Modes”.