Mike,

Triggers don't exist for fields only for tables. The three triggers are Update, Delete, and Insert. They cover the three things that can happen to a record in a table. They are like table events in that whenever there is an attempt to update an existing record the Update trigger fires, to delete a record the delete trigger fires and to add a new record the Insert trigger fires. The triggers can call UDF that can be defined in the DBC's stored procedures or elsewhere. The UDF's can return .T. (the trigger succeeded and the operation is allowed to complet) or .F. (the trigger failed and the operation is aborted).

Triggers are most commonly used for enforcing referential integrity. The limitations for triggers is that a trigger may not cause any change to the table for which it fired.