exists_predicate

version 11

EXISTS (subquery)

An exists_predicate is used to indicate a subquery and then check whether it returns anything. This is done by passing the EXISTS keyword followed by the subquery.

This example returns the total sales when there is a store in the region specified:

   SELECT SUM (Sales)
       FROM Store_Information
       WHERE EXISTS
         (SELECT * FROM Geography
         WHERE region_name = 'West')

predicate, subquery.