What is a trigger in a database?

A trigger in a database is defined as a set of instructions that are automatically executed in response to certain events on a table, such as insertion, update, or deletion of data. This functionality is essential for enforcing business rules at the database level without requiring application-level logic to handle them. For example, a trigger can automatically update a timestamp column whenever a record is modified or ensure that specific conditions are met before allowing a change to the data. By using triggers, database administrators can maintain data integrity, enforce constraints, and automate system tasks effectively, enhancing the automated behavior of the database in response to user actions or system events.