Such trigger actions need to know one or both of the following:
- The "before" values of the rows being changed (their values before the
database event that caused the trigger to fire)
- The "after" values of the rows being changed (the values to which the
database event is setting them)
provides transition
variables and transition tables for a trigger action to access these values.
See "Referencing old and new values: the REFERENCING clause" under the "CREATE
TRIGGER statement" topic in the
.