GATE CS 2021 Set 2 — Question 16

MCQ+1 / -0.33EasyKeys (Super, Candidate, Foreign)Relational ModelDatabases

Databases → Relational Model → Keys (Super, Candidate, Foreign)

Last updated 5 September 2026

Question

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Correct answer (D) Both S1 and S2 are false. Solution S1 is false: A relation scheme can have multiple foreign keys. For example, an 'Enrollment' table might have one foreign key referring to 'Students' and another referring to 'Courses'. S2 is false: A foreign key can refer to the same relation it is defined in. This is known as a self-referencing foreign key. A common example is an 'Employee' table where a 'ManagerID' column is a foreign key referring to the 'EmployeeID' column of the same table. Therefore, both statements are false. Turn this into a strength. Explore AI-powered practice and doubt support with Success Tracker.

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Correct answer (D) Both S1 and S2 are false. Solution S1 is false: A relation scheme can have multiple foreign keys. For example, an 'Enrollment' table might have one foreign key referring to 'Students' and another referring to 'Courses'. S2 is false: A foreign key can refer to the same relation it is defined in. This is known as a self-referencing foreign key. A common example is an 'Employee' table where a 'ManagerID' column is a foreign key referring to the 'EmployeeID' column of the same table. Therefore, both statements are false.

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