Question

Consider the following SQL DDL statements:
CREATE TABLE DEPT ( did INTEGER,
dname VARCHAR(20),
PRIMARY KEY(did));

CREATE TABLE EMP( eid INTEGER,
name VARCHAR(20),
did INTEGER,
PRIMARY KEY(eid),
FOREIGN KEY(did) REFERENCES DEPT);

In the database created by above statements, which of the following operations may cause violation
of referential integrity constraints?

Question 1 options:

	UPDATE on DEPT
	INSERT into DEPT
	DELETE on EMP
	Both DELETE on EMP and INSERT into DEPT

Answer 1

Solution

DELETE on EMP

Explanation In the DEPT table there are no referential integrity that means no foreign key if you insert any values or update values it will not cause any violation for e.g

as you can see we are inserting 2 new records and updating existing records in the DEPT violation there are no violation

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but deleting a record cause referential integrity violation because

FOREIGN KEY(did) REFERENCES DEPT);

did is the foreign key

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all the best