What is the primary use of a database trigger?

A database trigger is primarily used to enforce business rules automatically in response to specific events that occur within the database. When a trigger is defined, it is set to execute a set of predefined actions when certain conditions are met, such as before or after data is inserted, updated, or deleted from a table.

This automatic enforcement of business rules ensures that the integrity of the data is maintained without requiring additional coding within the application layer. For example, if there is a rule that prohibits any employee from being assigned to more than one department, a trigger can automatically roll back any attempts to violate that rule during an insert or update operation.

In contrast, improving query performance, generating reports, and managing user permissions are functions that are handled through other means within the database management system (DBMS) and are not the primary role of triggers. Query performance can be enhanced through indexing and query optimization, report generation typically involves separate reporting tools or querying techniques, and user permission management falls under security policies and user authentication, which are independent of the trigger mechanism.