Trigger:

• A trigger defines a set of actions that are performed in response to an insert, update, or delete operation on a specified table.
• When such an SQL operation is executed, the trigger is said to have been activated. Triggers are optional and are defined using the CREATE TRIGGER statement.

Types:

1. INSERT
2. UPDATE
3. DELETE.

Uses:

• The main purpose of triggers is to automate execution of code when an event occurs.
• In other words, if you need a certain piece of code to always be executed in response to an event, the best option is to use triggers.