However if the trigger actions reference other tables, the trigger is not dropped or modified if those other tables are dropped or modified.Triggers are removed using the DROP TRIGGER statement.
Such a trigger will only fire when changes are made to the target table by the application that defined the trigger.
Now, you just have to create your trigger like so: This technique is very useful when you don't want to have to rely on your application developers to always remember to update the time stamps. You should note that you will have to create a separate trigger for each table, which isn't a big deal. If you attempt to use AFTER UPDATE you put yourself into an infinite loop!
The CREATE TRIGGER statement is used to add triggers to the database schema.
FOR EACH ROW implies that the SQL statements specified in the trigger may be executed (depending on the WHEN clause) for each database row being inserted, updated or deleted by the statement causing the trigger to fire.
Both the WHEN clause and the trigger actions may access elements of the row being inserted, deleted or updated using references of the form "NEW.column-name" and "OLD.column-name", where column-name is the name of a column from the table that the trigger is associated with.