Oracle Designer Model, Release 6i
Uniqueness Criteria

TRIGGER_COLUMN_USAGE

Uniqueness may be enforced by database constraints and/or the API, depending on the complexity of the uniqueness criteria

• Database constraints are used when the uniqueness criteria can be expressed simply as a combination of columns. These are defined as unique key constraints placed on the underlying table.
• The API is used when the uniqueness criteria cannot be expressed simply as a combination of columns. These are defined in PL/SQL.

Uniqueness enforced by database constraints

The following unique key constraints exist for the underlying table SDD_TRGCOL

Unique Key Constraint	Column
UK_TRGCOL	( 1 ) DATABASE_TRIGGER_REF ( 2 ) COLUMN_REF

Uniqueness enforced in PL/SQL by the API

See API Spec for TRIGGER_COLUMN_USAGE