How To Update Values on Multiple Rows? - MySQL FAQs - Understanding SQL INSERT, UPDATE and DELETE Statements

If the WHERE clause in an UPDATE matches multiple rows, the SET clause will be applied to all matched rows. This rule allows you to update values on multiple rows in a single UPDATE statement. Here is a good example:

mysql> UPDATE fyi_links SET counts = 9, notes = 'Wrong' 
   WHERE id >= 500;
Query OK, 5 rows affected (0.00 sec)
Rows matched: 5  Changed: 5  Warnings: 0

mysql> SELECT id, url, notes, counts, DATE(created) 
   FROM fyi_links WHERE id >= 500;
+-----+-------------------+-------+--------+---------------+
| id  | url               | notes | counts | DATE(created) |
+-----+-------------------+-------+--------+---------------+
| 601 | moc.retneciyf.ved | Wrong |      9 | 2006-04-30    |
| 602 | moc.retneciyf.abd | Wrong |      9 | 2006-08-31    |
| 603 | moc.retneciyf.aqs | Wrong |      9 | 2006-08-31    |
| 610 |                   | Wrong |      9 | 2006-08-31    |
| 500 | moc.retneciyf.www | Wrong |      9 | 2006-08-31    |
+-----+-------------------+-------+--------+---------------+
5 rows in set (0.00 sec)

This statement updated 5 rows with the same new values on all 5 rows.