Sorting by Time of Day

6.11.1 Problem

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

6.11.2 Solution

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

6.11.3 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);
+---------------------+---------+---------+---------+---------+---------+
| 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 |
...

Using the mysql Client Program

Writing MySQL-Based Programs

Record Selection Techniques

Working with Strings

Working with Dates and Times

Sorting Query Results

Generating Summaries

Modifying Tables with ALTER TABLE

Obtaining and Using Metadata

Importing and Exporting Data

Generating and Using Sequences

Using Multiple Tables

Statistical Techniques

Handling Duplicates

Performing Transactions

Introduction to MySQL on the Web

Incorporating Query Resultsinto Web Pages

Processing Web Input with MySQL

Using MySQL-Based Web Session Management

Appendix A. Obtaining MySQL Software

Appendix B. JSP and Tomcat Primer

Appendix C. References



MySQL Cookbook
MySQL Cookbook
ISBN: 059652708X
EAN: 2147483647
Year: 2005
Pages: 412
Authors: Paul DuBois

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