GATE | GATE CS 1999 | Question 50

Which of the following is/are correct?
(A) An SQL query automatically eliminates the duplicates
(B) An SQL query will not work if there are no indexes on the relations
(C) SQL permits attribute names to be repeated in the same relation
(D) None of the above


Answer: (D)

Explanation: An SQL does not remove duplicates like relational algebra projection, we have to remove it using distinct.
An SQL will work slowly but surely if there are no indexes.
An SQL does not permit 2 attributes of same name in a relation.

So, none of the options (a), (b) and (c) are correct. Hence, option (d) is Answer.


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