Application programming uses SQL embedded in triggers, stored procedures, and other program code to accomplish a specific task.
A trigger is a stored program that is executed by the DBMS whenever a specified event occurs on a specified table or view (defined in Chapter Seven).
Triggers are used to enforce specific minimum cardinality enforcement actions not otherwise programmed into the DBMS.
Triggers will be discussed in detail in Chapters 7, 10 (SQL Server), 10A (Oracle Database),and 10B (MySQL 5.5).