A trigger in MySQL is a database object that is associated with a table. A
trigger is fired, when a particular event occurs for the table. Triggers are
used to perform validation checks on data values for insertion or to perform
calculations on values for updation.
They are 2 types of triggers – Before Trigger and After Trigger. Before Trigger
fires before the execution of INSERT, DELETE and UPDATE commands. After trigger
fires after the execution of INSERT, DELETE and UPDATE commands.