5.5 Decomposing Dates and Times Using Formatting Functions
5.5.1 Problem
You
want to obtain just a part of a
date or a time.
5.5.2 Solution
Use a formatting function such as
DATE_FORMAT( ) or TIME_FORMAT( )
with a format string that includes a specifier for the part of the
value you want to obtain.
5.5.3 Discussion
MySQL provides several options for decomposing dates or times to
obtain their component values. The DATE_FORMAT( )
and TIME_FORMAT( ) functions provide one way to
extract individual parts of temporal values:
mysql> SELECT dt,
-> DATE_FORMAT(dt,'%Y') AS year,
-> DATE_FORMAT(dt,'%d') AS day,
-> TIME_FORMAT(dt,'%H') AS hour,
-> TIME_FORMAT(dt,'%s') AS second
-> FROM datetime_val;
+---------------------+------+------+------+--------+
| dt | year | day | hour | second |
+---------------------+------+------+------+--------+
| 1970-01-01 00:00:00 | 1970 | 01 | 00 | 00 |
| 1987-03-05 12:30:15 | 1987 | 05 | 12 | 15 |
| 1999-12-31 09:00:00 | 1999 | 31 | 09 | 00 |
| 2000-06-04 15:45:30 | 2000 | 04 | 15 | 30 |
+---------------------+------+------+------+--------+
Formatting functions allow you to extract more than one part of a
value. For example, to extract the entire date or time from
DATETIME values, do this:
mysql> SELECT dt,
-> DATE_FORMAT(dt,'%Y-%m-%d') AS 'date part',
-> TIME_FORMAT(dt,'%T') AS 'time part'
-> FROM datetime_val;
+---------------------+------------+-----------+
| dt | date part | time part |
+---------------------+------------+-----------+
| 1970-01-01 00:00:00 | 1970-01-01 | 00:00:00 |
| 1987-03-05 12:30:15 | 1987-03-05 | 12:30:15 |
| 1999-12-31 09:00:00 | 1999-12-31 | 09:00:00 |
| 2000-06-04 15:45:30 | 2000-06-04 | 15:45:30 |
+---------------------+------------+-----------+
One advantage of using formatting functions is that you can display
the extracted values in a different form than that in which
they're present in the original values. If you want
to present a date differently than in
CCYY-MM-DD format or present a time
without the seconds part, that's easy to do:
mysql> SELECT ts,
-> DATE_FORMAT(ts,'%M %e, %Y') AS 'descriptive date',
-> TIME_FORMAT(ts,'%H:%i') AS 'hours/minutes'
-> FROM timestamp_val;
+----------------+-------------------+---------------+
| ts | descriptive date | hours/minutes |
+----------------+-------------------+---------------+
| 19700101000000 | January 1, 1970 | 00:00 |
| 19870305123015 | March 5, 1987 | 12:30 |
| 19991231090000 | December 31, 1999 | 09:00 |
| 20000604154530 | June 4, 2000 | 15:45 |
+----------------+-------------------+---------------+
5.5.4 See Also
Recipe 5.6 discusses other functions that may be
used to extract single components from dates or times. Recipe 5.7 shows how to use substring functions for
component extraction.
|
