Differences between transitional and non-transitional constraints
Transitional constraints and non-transitional constraints are different in several ways:
•Only transitional constraints can refer to OLD column values.
•Only transitional constraints can be restricted to be evaluated only on INSERT, UPDATE, or DELETE manipulations.
•Transitional multi-record constraints are only evaluated when the transition table is manipulated, not when other tables mentioned in the constraint SQL statements are manipulated.
•Transitional table constraints are always handled as soon as the record is stored (record validation). Handling cannot be delayed until commit, because the Rules Engine only remembers old column values for the current row event. For this reason, transitional constraints can NOT be set to Deferred.
•Existing data cannot be checked against transitional constraints by generating BenchMark constraint violation reports. These only report on non-transitional constraints.