What can I do with scheduled events in MySQL?
MySQL Events can be very useful in many cases such as optimizing database tables, cleaning up logs, archiving data, or generating complex reports during off-peak time. MySQL uses a special thread called event scheduler thread to execute all scheduled events.
How to create a new event in MySQL?
Creating new MySQL events. The CREATE EVENT statement creates a new event. Here is the basic syntax of the CREATE EVENT statement: CREATE EVENT [ IF NOT EXIST] event_name ON SCHEDULE schedule DO event_body. Code language: SQL (Structured Query Language) (sql) In this syntax:
Why are MySQL events known as temporal triggers?
MySQL Events are also known as “temporal triggers” because they are triggered by time, not by DML events like normal triggers. MySQL events are similar to a cronjob on Linux or a task scheduler on Windows. MySQL Event Scheduler manages the schedule and execution of Events.
Why does MySQL show no row when event is expired?
To shows all events in the database, you use the following statement: The output shows no row because the event is automatically dropped when it is expired. In this case, it is a one-time event and expired when its execution completed. To keep the event after it is expired, you use the ON COMPLETION PRESERVE clause.
How to remove an event from MySQL database?
To remove an existing event, you use the DROP EVENT statement as follows: DROP EVENT [ IF EXIST] event_name; For example, to drop the test_event_03 event, you use the following statement: DROP EVENT IF EXIST test_event_03; In this tutorial, you have learned about MySQL events and how to create and delete events from a database.
Can you change the event scheduler state at runtime?
In addition, the Event Scheduler state cannot be changed at runtime. If the Event Scheduler status has not been set to DISABLED , event_scheduler can be toggled between ON and OFF (using SET ). It is also possible to use 0 for OFF, and 1 for ON when setting this variable.
How to show events in a schema in MySQL?
It requires the EVENT privilege for the database from which the events are to be shown. In its simplest form, SHOW EVENTS lists all of the events in the current schema: To see events for a specific schema, use the FROM clause. For example, to see events for the test schema, use the following statement: