共用方式為

Trigger Usage

  • 發行項

A trigger is an expression that is bound to a table and is invoked when any of the table's records are modified by one of the specified data-modification commands. Triggers can be used to perform any side-effect operations that a database application requires when data is modified. For example, you can use triggers to:

  • Log database modifications.
  • Enforce referential integrity.
  • Create an automatic reorder for a product that is low on stock.

Triggers are created and stored as properties on a specific table. If you remove a table from a database, the triggers associated with that table are deleted. Triggers fire after all other checks, such as validation rules, primary key enforcement, and null value enforcement, are performed. And unlike field- and record-level validation rules, triggers don't fire on buffered data.

See Also

Record-Level Rule Checking | Creating Triggers | Working with Tables | Removing or Deleting Triggers | Modifying Triggers