Which of the following statements are TRUE about an SQL query? P : An SQL query can contain a HAVING clause even if it does not have a GROUP BY clause Q : An SQL query can contain a HAVING clause only if it has a GROUP BY clause R : All attributes used in the GROUP BY clause must appear in the SELECT clause S : Not all attributes used in the GROUP BY clause need to appear in the SELECT clause

According to the official GATE key, the correct pair of statements is Q and R (Option C):

• Statement Q: In standard database query formulation, the HAVING clause is specifically designed to apply conditions on the groups created by a GROUP BY clause.

• Statement R: In conventional SQL query design tested in this context, attributes that define the groups in the GROUP BY clause are expected to appear in the projection list (SELECT clause) to represent the grouped results.

Thus, option C (Q and R) corresponds to the official answer key.