Question

Let r1(a, b, c) and r2(x, y, z) be two relations in which a is the foreign key of r1 that refers to the primary key of r2. consider following four options.

(a) Insert into R1 (b) Insert into R2
(c) Delete from R1 (d) Delete from R2
Which of the following is correct about the referential integrity constraint with respect to above?
a. Operations (a) and (b) will cause violation.
b.Operations (b) and (c) will cause violation.
c.Operations (c) and (d) will cause violation.
d.Operations (d) and (a) will cause violation.

Answer 1

Inserting into R1 requires a matching primary key in R2 while deleting from R2 could break the referential link. The correct answer regarding referential integrity constraint violations is (c) Operations (c) and (d).

Step-by-step explanation:

Referential integrity ensures that relationships between tables remain consistent. In this scenario, with a foreign key in R1 referring to the primary key in R2, the following cases are considered. If you delete a record from R1, it might violate referential integrity if there are related records in R2. The foreign key constraint in R1 ensures that a corresponding record in R2 exists. If you attempt to delete a record from R2 that has related records in R1, it will violate referential integrity. The foreign key constraint in R1 depends on the existence of the corresponding primary key in R2.

Operations (a) and (b) involve insertions and will not cause referential integrity violations because they are about adding new records, not deleting existing ones. Therefore, (c) and (d) are the operations that may lead to referential integrity violations in this scenario.