Go Up to Triggers (Data Definition Guide)
Triggers are a powerful feature with a variety of uses. Among the ways that triggers can be used are:
- To make correlated updates. For example, to keep a log file of changes to a database or table.
- To enforce data restrictions, so that only valid data is entered in tables.
- Automatic transformation of data. For example, to automatically convert text input to uppercase.
- To notify applications of changes in the database using event alerters.
- To perform cascading referential integrity updates.
Triggers are stored as part of a database, like stored procedures and exceptions. Once defined to be
ACTIVE, they remain active until deactivated with
ALTER TRIGGER or removed from the database with
A trigger is never explicitly called. Rather, an active trigger automatically fires when the specified action occurs on the specified table.
- Triggers and Transactions
- Triggers and Security
- Triggers as Event Alerters
- Updating Views with Triggers