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.

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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