With the help of ALTER EVENT statement, we can modify an existing MySQL event. We can change the various attributes of an event. ALTER EVENT has the following syntax −
ALTER EVENT event_name ON SCHEDULE schedule ON COMPLETION [NOT] PRESERVE RENAME TO new_event_name ENABLE | DISABLE DO event_body
To understand it we are illustrating the example as below −
Example
Suppose we have an event as follows −
mysql> Create event hello ON SCHEDULE EVERY 1 Minute DO INSERT INTO event_messages(message, generated_at) Values ('Alter event testing', NOW()); Query OK, 0 rows affected (0.00 sec) mysql> select * from event_messages; +----+---------------------+---------------------+ | ID | MESSAGE | Generated_at | +----+---------------------+---------------------+ | 1 | Without Preserve | 2017-11-22 20:32:13 | | 2 | With Preserve | 2017-11-22 20:35:12 | | 3 | Alter event testing | 2017-11-22 21:08:37 | +----+---------------------+---------------------+ 3 rows in set (0.00 sec) mysql> ALTER EVENT hello ON SCHEDULE EVERY 2 MINUTE; Query OK, 0 rows affected (0.00 sec)
The above query will alter the schedule of the event from 1 minute to 2 minutes. And the query below will change the body of the event.
mysql> ALTER EVENT hello DO INSERT INTO event_messages(message,generated_at) VALUES('ALTERED',NOW()); Query OK, 0 rows affected (0.00 sec) mysql> select * from event_messages; +----+---------------------+---------------------+ | ID | MESSAGE | Generated_at | +----+---------------------+---------------------+ | 1 | Without Preserve | 2017-11-22 20:32:13 | | 2 | With Preserve | 2017-11-22 20:35:12 | | 3 | Alter event testing | 2017-11-22 21:08:37 | | 4 | Alter event testing | 2017-11-22 21:09:15 | | 5 | ALTERED | 2017-11-22 21:11:15 | +----+---------------------+---------------------+ 5 rows in set (0.00 sec)
The above result set shows that we got the changed message after 2 minutes.