MySQL trigger

1、 Introduce

      ① trigger , Is a special stored procedure . A trigger, like a stored procedure, is a function that can perform a specific function 、 Stored on the database server SQL fragment , But the trigger Don't need to call , When executing... On the data in the database table DML This is triggered automatically during operation SQL Execution of fragments , There is no need to manually strip .

      ② stay MySQL in , Only execute insert,delete,update operation Trigger execution can only be triggered when

      ③ This feature of trigger can help to ensure the integrity of data in database , logging , Data verification and other operations