UGC NET CSE | December 2004 | Part 2 | Question: 18

Question

The completeness constraint has rules :

• A. Supertype, Subtype
• B. Total specialization, Partial specialization
• C. Specialization, Generalization
• D. All of the above

Answer 1

Answer: B)Total specialization, Partial specialization

The completeness constraint specifies whether or not an entity in the higher-level entity set must belong to at least one of the lower-level entity sets within the generalization/specialization.

This constraint can be one of the following

1.  Total specialization:Each higher-level entity(Super Type) must belong to a lower-level entity set(Subtype).

2. Partial specialization: Some higher-level entities(SuperType) may not belong to any lower-level entity set(Subtype).