Databases Intermediate

What is Trigger?

A database object that automatically executes a specified function when certain events (INSERT, UPDATE, DELETE) occur on a table.

Triggers run automatically in response to data changes. They can execute BEFORE or AFTER the triggering event, and operate on each row or once per statement. Common uses include audit logging, data validation, maintaining derived data, and enforcing complex business rules.

In PostgreSQL, triggers call trigger functions written in PL/pgSQL. While powerful, overuse of triggers can make database behavior hard to debug and predict. Consider application-level logic for complex business rules.

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