ER and Relational model

Question 1
 
A
Both (i) and (ii) will fail
B
(i) will fail but (ii) will succeed
C
(i) will succeed but (ii) will fail
D
Both (i) and (ii) will succeed
       Database Management System       ER and Relational model       Gate 2004-IT
Question 1 Explanation: 
Here in (i), when we update in Student table, Dept_id = Null, then it will not cause any problem to referenced table.
But in (ii) if we set in Department table, Dept_id = Null, then it will produce inconsistency because in Student table we will still have the tuples containing the Dept_id = 1.
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