GATE | GATE CS 2012 | Question 50

Consider the following relations A, B, C. How many tuples does the result of the following relational algebra expression contain? Assume that the schema of A U B is the same as that of A. 

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

(A)

7

(B)

4

(C)

5

(D)

9

Answer: (A)
Explanation:

See https://www.geeksforgeeks.org/database-management-system-set-3/amp/

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