Oracle Designer Model, Release 6i
Uniqueness Criteria

RELATION_SELECTION

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_VWTAB

Unique Key Constraint	Column
UK_VWTAB	( 1 ) VIEW_REF ( 2 ) TABLE_REF ( 3 ) SEQUENCE_NUMBER

Uniqueness enforced in PL/SQL by the API

See API Spec for RELATION_SELECTION