Question 8735 – SQL
May 4, 2024Question 8403 – SQL
May 4, 2024Question 5943 – SQL
Which construct in SQL is used to test whether a subquery has any tuples in its result ?
Correct Answer: B
Question 159 Explanation:
EXISTS:The EXISTS function in SQL is used to check whether the result of a correlated
nested query is empty (contains no tuples) or not.
UNIQUE: UNIQUE(Q), which returns TRUE if there are no duplicate tuples in the result of query ; otherwise, it returns FALSE. This can be
used to test whether the result of a nested query is a set or a multiset.
GROUP BY: The GROUP BY clause specifies the grouping attributes, which should also appear in the SELECT clause, so that the value resulting from applying each aggregate function to a group of tuples appears along with the value of the grouping attribute(s).
EXCEPT: The EXCEPT query is like the set difference operation in SQL. The difference between EXCEPT and EXCEPT ALL is EXCEPT do not allow duplicates while EXCEPT ALL allows duplicates in the result of a query.
Hence correct answer is OPTION(B)
nested query is empty (contains no tuples) or not.
UNIQUE: UNIQUE(Q), which returns TRUE if there are no duplicate tuples in the result of query ; otherwise, it returns FALSE. This can be
used to test whether the result of a nested query is a set or a multiset.
GROUP BY: The GROUP BY clause specifies the grouping attributes, which should also appear in the SELECT clause, so that the value resulting from applying each aggregate function to a group of tuples appears along with the value of the grouping attribute(s).
EXCEPT: The EXCEPT query is like the set difference operation in SQL. The difference between EXCEPT and EXCEPT ALL is EXCEPT do not allow duplicates while EXCEPT ALL allows duplicates in the result of a query.
Hence correct answer is OPTION(B)
UNIQUE
EXISTS
GROUP BY
EXCEPT
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