GATE | GATE CS 2012 | Question 51
Table A
Id Name Age
----------------
12 Arun 60
15 Shreya 24
99 Rohit 11
Table B
Id Name Age
----------------
15 Shreya 24
25 Hari 40
98 Rohit 20
99 Rohit 11
Table C
Id Phone Area
-----------------
10 2200 02
99 2100 01
Consider the above tables A, B and C. How many tuples does the result of the following SQL query contains?
SELECT A.id
FROM A
WHERE A.age > ALL (SELECT B.age
FROM B
WHERE B. name = "arun")
(A) 4
(B) 3
(C) 0
(D) 1
Answer: (B)
Explanation: The meaning of “ALL” is the A.Age should be greater than all the values returned by the subquery. There is no entry with name “arun” in table B. So the subquery will return NULL. If a subquery returns NULL, then the condition becomes true for all rows of A (See this for details). So all rows of table A are selected.
Source: https://www.geeksforgeeks.org/database-management-system-set-3/
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Last Updated :
28 Jun, 2021
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