The following SQL statement contains which type of subquery?
SELECT title FROM books WHERE EXISTS
(SELECT isbn FROM orderitems WHERE books.isbn = orderitems.isbn);
A) multiple-column
B) inline view
C) correlated
D) uncorrelated

Question

​The following SQL statement contains which type of subquery?
SELECT title FROM books WHERE EXISTS
(SELECT isbn FROM orderitems WHERE books.isbn = orderitems.isbn);
A) ​multiple-column
B) ​inline view
C) ​correlated
D) ​uncorrelated

Quizplus · Accepted Answer

The subquery is correlated because it references a column from the outer query (books.isbn) in the WHERE clause of the subquery. Specifically, it checks whether there exists an orderitem with the same isbn as the outer query's book.

​The Following SQL Statement Contains Which Type of Subquery

The Following SQL Statement Contains Which Type of Subquery