Mysql trigger

Database trigger is a stored program executed automatically to respond to a specific event e.g., insert, update or delete occurred in a table.The trigger is mostly used for maintaining the integrity of the information on the database So Trigger automatic done the event
TRIGGER trigger_name
trigger_time trigger_event
ON tbl_name FOR EACH ROW

trigger_time: { BEFORE | AFTER }

trigger_event: { INSERT | UPDATE | DELETE }

trigger_order: { FOLLOWS | PRECEDES } other_trigger_name

trigger_time is the trigger action time. It can be BEFORE or AFTER to indicate that the trigger activates before or after each row to be modified.

trigger_event indicates the kind of operation that activates the trigger. These trigger_event values are permitted:

  • INSERT: The trigger activates whenever a new row is inserted into the table; for example, through INSERT, LOAD DATA, and REPLACE statements.
  • UPDATE: The trigger activates whenever a row is modified; for example, through UPDATE statements.
  • DELETE: The trigger activates whenever a row is deleted from the table; for example, through DELETE and REPLACE statements. DROP TABLE and TRUNCATE TABLE statements on the table do not activate this trigger, because they do not use DELETE. Dropping a partition does not activate DELETE triggers, either.