Using the NOT keyword with the
EXISTS keyword allows you to test whether rows do not exist in the result of the subquery. For every row the outer query evaluates, Pervasive PSQL tests for the existence of a related row from the subquery. Pervasive PSQL excludes from the statement's result table each row from the outer query that corresponds to a related row from the subquery.
Including the NOT keyword along with the
IN operator allows you to test whether the result of the outer query is not included in the result of the subquery. The result table for the statement includes only rows the outer query returns that do not have a related row from the subquery.