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GATE Overflow Test Series | Databases | Test 1 | Question: 5

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Let $A (a, b, c)$ and $B(d, e, f)$ be two relations in which $d$ is the foreign key of $B$ that refers to the primary key of $A$.

Which of the following four operations on $A$ and $B$ will not cause a violation of the referential integrity constraint? (Mark all the appropriate choices)

  1. Insert into $A$
  2. Delete from $A$
  3. Insert into $B$
  4. Delete from $B$
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Foreign key in B is referring to the primary key in A. So, a referential integrity can be violated when

1. Insert happens on B - when the referred key value may not be in A

2. Delete happens on A - when the deleted key value is being referred by some B tuple

Delete from B and Insert into A cannot cause referential integrity violation.

Correct option: A; D
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