# Events Overview
[Events](https://mariadb.com/docs/server/server-usage/triggers-events) are named database objects containing SQL statements that are to be executed at a later stage, either once off, or at regular intervals.
They function very similarly to the Windows Task Scheduler or Unix cron jobs.
Creating, modifying or deleting events requires the [EVENT privilege](https://mariadb.com/docs/server/reference/sql-statements/account-management-sql-statements/grant#database-privileges).
## Creating Events
Events are created with the [CREATE EVENT](https://mariadb.com/docs/server/reference/sql-statements/data-definition/create/create-event) statement.
### Example
```sql
CREATE EVENT test_event
ON SCHEDULE EVERY 1 MINUTE DO
UPDATE test.t1 SET a = a + 1;
```
## Executing Events
Events are only executed if the event scheduler is running. This is determined by the value of the [event\_scheduler](https://mariadb.com/docs/server/server-management/variables-and-modes/server-system-variables#event_scheduler) system variable, which needs to be set to `On` for the event scheduler to be running.
You can check if the Event scheduler is running with:
```sql
SHOW PROCESSLIST;
+----+-----------------+-----------+------+---------+------+-----------------------------+------------------+----------+
| Id | User | Host | db | Command | Time | State | Info | Progress |
+----+-----------------+-----------+------+---------+------+-----------------------------+------------------+----------+
| 40 | root | localhost | test | Sleep | 4687 | | NULL | 0.000 |
| 41 | root | localhost | test | Query | 0 | init | SHOW PROCESSLIST | 0.000 |
| 42 | event_scheduler | localhost | NULL | Daemon | 30 | Waiting for next activation | NULL | 0.000 |
+----+-----------------+-----------+------+---------+------+-----------------------------+------------------+----------+
```
If the event scheduler is not running and `event_scheduler` has been set to `OFF`, use:
```sql
SET GLOBAL event_scheduler = ON;
```
to activate it. If `event_scheduler` has been set to `Disabled`, you cannot change the value at runtime. Changing the value of the `event_scheduler` variable requires the SUPER privilege.
Since [MariaDB 10.0.22](https://app.gitbook.com/s/aEnK0ZXmUbJzqQrTjFyb/community-server/old-releases/10.0/10.0.22), setting the [event\_scheduler](https://mariadb.com/docs/server/server-management/variables-and-modes/server-system-variables#event_scheduler) system variable will also try to reload the [mysql.event table](https://mariadb.com/docs/server/reference/system-tables/the-mysql-database-tables/mysql-event-table) if it was not properly loaded at startup.
## Viewing Current Events
A list of current events can be obtained with the [SHOW EVENTS](https://mariadb.com/docs/server/reference/sql-statements/administrative-sql-statements/show/show-events) statement. This only shows the event name and interval - the full event details, including the SQL, can be seen by querying the [Information Schema EVENTS table](https://mariadb.com/docs/server/reference/system-tables/information-schema/information-schema-tables/information-schema-events-table), or with [SHOW CREATE EVENT](https://mariadb.com/docs/server/reference/sql-statements/administrative-sql-statements/show/show-create-event).
If an event is currently being executed, it can be seen by querying the [Information Schema PROCESSLIST table](https://mariadb.com/docs/server/reference/system-tables/information-schema/information-schema-tables/information-schema-processlist-table), or with the [SHOW PROCESSLIST](https://mariadb.com/docs/server/reference/sql-statements/administrative-sql-statements/show/show-processlist) statement.
### Example
```sql
SHOW EVENTS\G;
*************************** 1. row ***************************
Db: test
Name: test_event
Definer: root@localhost
Time zone: SYSTEM
Type: RECURRING
Execute at: NULL
Interval value: 1
Interval field: MINUTE
Starts: 2013-05-20 13:46:56
Ends: NULL
Status: ENABLED
Originator: 1
character_set_client: utf8
collation_connection: utf8_general_ci
Database Collation: latin1_swedish_ci
```
```
SHOW CREATE EVENT test_event\G
*************************** 1. row ***************************
Event: test_event
sql_mode:
time_zone: SYSTEM
Create Event: CREATE DEFINER=`root`@`localhost` EVENT `test_event` ON SCHEDULE EVERY 1 MINUTE STARTS '2013-05-20 13:46:56' ON COMPLETION NOT PRESERVE ENABLE DO UPDATE test.t1 SET a = a + 1
character_set_client: utf8
collation_connection: utf8_general_ci
Database Collation: latin1_swedish_ci
```
## Altering Events
An event can be changed with the [ALTER EVENT](https://mariadb.com/docs/server/server-usage/triggers-events/event-scheduler/alter-event) statement.
### Example
```sql
ALTER EVENT test_event ON SCHEDULE EVERY '2:3' DAY_HOUR;
```
## Dropping Events
Events are dropped with the [DROP EVENT](https://mariadb.com/docs/server/reference/sql-statements/data-definition/drop/drop-event) statement. Events are also automatically dropped once they have run for the final time according to their schedule, unless the ON COMPLETION PRESERVE clause has been specified.
### Example
```sql
DROP EVENT test_event;
Query OK, 0 rows affected (0.00 sec)
```
## See Also
* [CREATE EVENT](https://mariadb.com/docs/server/reference/sql-statements/data-definition/create/create-event)
* [SHOW CREATE EVENT](https://mariadb.com/docs/server/reference/sql-statements/administrative-sql-statements/show/show-create-event)
* [ALTER EVENT](https://mariadb.com/docs/server/server-usage/triggers-events/event-scheduler/alter-event)
* [DROP EVENT](https://mariadb.com/docs/server/reference/sql-statements/data-definition/drop/drop-event)
* [Event Limitations](https://mariadb.com/docs/server/server-usage/triggers-events/event-scheduler/event-limitations)
* [Automating MariaDB Tasks with Events](https://mariadb.com/docs/server/server-management/automated-mariadb-deployment-and-administration/automating-mariadb-tasks-with-events)
*This page is licensed: CC BY-SA / Gnu FDL*
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