What is a trigger. What are different type of triggers in MySQL?

A MySQL trigger is a named database object that is associated with a table and automatically activates in response to specific events on that table, such as INSERT, UPDATE, or DELETE operations[2][3][5]. Triggers are used for various purposes, including enforcing business rules, validating data, maintaining audit trails, and synchronizing tables.

Types of Triggers in MySQL

MySQL supports several types of triggers, which can be categorized based on the timing of their activation relative to the data modification event:

1. BEFORE Triggers: These triggers activate before a specified data modification event (INSERT, UPDATE, or DELETE) occurs on the table. They are often used for validating or modifying data before it is written into the table[3][7].

2. AFTER Triggers: These triggers activate after the data modification event. They are useful for actions that require the assurance that the data has already been modified, such as logging changes or updating other tables based on the changes in the main table[3][7].

3. INSTEAD OF Triggers: This type of trigger is used mainly in views, not in tables. It replaces the standard action of a data modification event with custom actions defined in the trigger[1].

4. COMPOUND Triggers: These are not explicitly mentioned in the standa...