27.4.4 事件元数据

To obtain metadata about events:

Event Scheduler Time Representation

Each session in MySQL has a session time zone (STZ). This is the session time_zone value that is initialized from the server's global time_zone value when the session begins but may be changed during the session.

The session time zone that is current when a CREATE EVENT or ALTER EVENT statement executes is used to interpret times specified in the event definition. This becomes the event time zone (ETZ); that is, the time zone that is used for event scheduling and is in effect within the event as it executes.

For representation of event information in the data dictionary, the execute_at, starts, and ends times are converted to UTC and stored along with the event time zone. This enables event execution to proceed as defined regardless of any subsequent changes to the server time zone or daylight saving time effects. The last_executed time is also stored in UTC.

Event times can be obtained by selecting from the Information Schema EVENTS table or from SHOW EVENTS, but they are reported as ETZ or STZ values. The following table summarizes representation of event times.

Value EVENTS Table SHOW EVENTS
Execute at ETZ ETZ
Starts ETZ ETZ
Ends ETZ ETZ
Last executed ETZ n/a
Created STZ n/a
Last altered STZ n/a