Machine-translated by Google. Questions are authored in English.
Top

Discussion

Which of the following is NOT a type of SQL constraint?

  • A.PRIMARY KEY
  • B.FOREIGN KEY
  • C.ALTERNATE KEY
  • D.
    UNIQUE

Answer: C

Correct answer: ALTERNATE KEY

SQL has PRIMARY KEY, FOREIGN KEY, UNIQUE, NOT NULL and CHECK. There is no ALTERNATE KEY constraint: an alternate key is a design concept, and it is enforced in SQL by declaring the column UNIQUE, which is exactly what an alternate key requires.

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.