What is trigger definition?

A trigger definition is a set of instructions or code that is executed automatically in response to a specific event or action that occurs in a database system. In database management systems, a trigger is a procedural code that is automatically executed in response to certain queries or actions on some database objects, such as tables, views, or indexes.

Triggers are typically used to enforce business rules or data integrity constraints in a database. They can be applied to many different events, such as data insertion, deletion, or modification. For example, a trigger might be defined to automatically update a table when a certain field is modified in another table, or to prevent data from being inserted into a table if it violates a certain rule.

Triggers can be defined in various programming languages, such as SQL or PL/SQL. They can also be defined to execute either before or after an event, depending on the specific requirements of the business rules or data integrity constraints being enforced.