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MySQL Cookbook
book

MySQL Cookbook

by Paul DuBois
October 2002
Intermediate to advanced content levelIntermediate to advanced
1024 pages
27h 26m
English
O'Reilly Media, Inc.
Content preview from MySQL Cookbook

Sorting by Time of Day

Problem

You want to sort in time-of-day order.

Solution

Pull out the hour, minute, and second from the column that contains the time, and use them for sorting.

Discussion

Time-of-day sorting can be done different ways, depending on your column type. If the values are stored in a TIME column, just sort them directly. To put DATETIME or TIMESTAMP values in time-of-day order, extract the time parts and sort them. For example, the mail table contains DATETIME values, which can be sorted by time of day like this:

mysql> SELECT * FROM mail ORDER BY HOUR(t), MINUTE(t), SECOND(t);
+---------------------+---------+---------+---------+---------+---------+
| t                   | srcuser | srchost | dstuser | dsthost | size    |
+---------------------+---------+---------+---------+---------+---------+
| 2001-05-15 07:17:48 | gene    | mars    | gene    | saturn  |    3824 |
| 2001-05-15 08:50:57 | phil    | venus   | phil    | venus   |     978 |
| 2001-05-16 09:00:28 | gene    | venus   | barb    | mars    |     613 |
| 2001-05-14 09:31:37 | gene    | venus   | barb    | mars    |    2291 |
| 2001-05-11 10:15:08 | barb    | saturn  | tricia  | mars    |   58274 |
| 2001-05-15 10:25:52 | gene    | mars    | tricia  | saturn  |  998532 |
| 2001-05-14 11:52:17 | phil    | mars    | tricia  | saturn  |    5781 |
| 2001-05-12 12:48:13 | tricia  | mars    | gene    | venus   |  194925 |
...

You can also use TIME_TO_SEC( ), which strips off the date part and returns the time part as the corresponding number of seconds:

mysql> SELECT * FROM mail ORDER BY TIME_TO_SEC(t); +---------------------+---------+---------+---------+---------+---------+ ...
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Publisher Resources

ISBN: 0596001452Catalog PageErrata