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

Discussion

In SQL, testing whether a subquery is empty is done using

  • A.DISTINCT
  • B.UNIQUE
  • C.NULL
  • D.EXISTS

Answer: D

Correct answer: EXISTS

EXISTS takes a subquery and yields true if it returns at least one row, so NOT EXISTS tests emptiness. DISTINCT and UNIQUE concern duplicates and NULL tests a single value.

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

Post your comment

Please log in or register to post a comment.