Types of PL/SQL Triggers and Their Purposes

PL/SQL triggers in Oracle database can be categorized into several different types based on their timing and the event that triggers them. Here are the main types of PL/SQL triggers:

• BEFORE Triggers: These triggers are fired before the triggering event (such as INSERT, UPDATE, DELETE) occurs on a table. They are commonly used to perform validation checks or data transformations before the actual operation takes place.
• AFTER Triggers: These triggers are executed after the triggering event has completed. They are often utilized for actions that need to be taken after the data manipulation operation has finished, such as logging the changes or sending notifications.
• INSTEAD OF Triggers: These triggers are used on views and are fired instead of the INSERT, UPDATE, or DELETE operations on the underlying tables. They provide a way to customize the behavior of the DML operations on views.
• COMPOUND Triggers: Introduced in Oracle 11g, compound triggers combine the functionality of BEFORE, AFTER, and INSTEAD OF triggers into a single trigger. This allows for more complex trigger logic to be implemented in a more efficient manner.

Each type of PL/SQL trigger serves a specific purpose and can be utilized to enforce business rules, maintain data integrity, or audit database operations. Understanding the differences between these trigger types is essential for effectively designing and implementing triggers in a PL/SQL environment.