Question

Which keyword is used to specify the foreign key after the table is created?

(a) SETUP

(b) SET

(c) ALTER TABLE

(d) SPECIFY

I have been asked this question in an interview for internship.

My question is taken from Foreign Keys and Referential Integrity in portion Using SQL to Manage Data of MySQL

Answer 1

The correct answer is (c) ALTER TABLE

Easiest explanation: When the table has already been created but the foreign key has not been set of foreign key constraints are not specified, the ‘ALTER TABLE – ADD FOREIGN KEY’ clause is used.