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?

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.


Quiz of this Question

GATE CS Corner    Company Wise Coding Practice

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