Transition properties

Previous Next

By default, constraints are non-transitional and all transition properties have no value. In contrast, transitional constraints have transition properties with default or specified values.

You can turn a constraint into a transitional constraint by setting transition properties or by using the OLD() function in the constraint SQL statements, or both.

This table lists the transition properties and their meaning.

Transition Properties

Transition Property

Meaning

Transition Table

Table for which the constraint is evaluated.

Alias

Alias identifying the table occurrence in the SQL statement for which the constraint is evaluated (if the table name is mentioned more than one time in the statement). For Example:

Transition Table: TOUR, Alias: T2

Fire on Insert

Always: Constraint is evaluated for each record being inserted into the transition table.

Never: Constraint is not evaluated when records are inserted into the transition table.

Fire on Delete

Always: Constraint is evaluated for each record being deleted from the transition table.

Never: Constraint is not evaluated when records are deleted from the transition table.

Fire on Update

UsedColumns: Constraint is evaluated whenever UPDATE manipulations occur on one or more of the columns of the transition table appearing in the constraint.

Always: Constraint is evaluated whenever UPDATE manipulations occur on any of the columns of the transition table.

Never: Constraint is not evaluated when records are updated in the transition table.

See also

Default transition properties

Changing default transition properties

Transitional constraints without OLD()