Question

The primary key must be

(a) Unique

(b) Not null

(c) Both Unique and Not null

(d) Either Unique or Not null

This question was addressed to me in class test.

The question is from Null Values Operations topic in chapter SQL : Queries, Constraints and Triggers of Database Management

Answer 1

Correct option is (c) Both Unique and Not null

Explanation: Primary key must satisfy unique and not null condition for sure.