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Modify an Existing MySQL Event
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.
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