When a trigger is set on a table does the application code wait for the original statement and the trigger to execute before resuming or just the original statement? Consider application code to be PHP or Ruby.Here by original statement I mean the sql query called by the application code.
2 Answers
Triggers in MySQL are synchronous. That means that the query submitter has to wait for the trigger to finish before it can resume its work.
When a trigger is set on a table, the code calling the trigger executes, and then the trigger executes. After the execution of the trigger, control is then returned back to the calling code to continue its execution from where it was interrupted.
The trigger has to execute first because other subsequent lines of the code may be relating to the table and may be trying to alter the table in a way that may be unacceptable to the set trigger.