Which two statements are true regarding the EXISTS operator used in the correlated subqueries? (Choose
two.)
A.
The outer query stops evaluating the result set of the inner query when the first value is found.
B.
It is used to test whether the values retrieved by the inner query exist in the result of the outer query.
C.
It is used to test whether the values retrieved by the outer query exist in the result set of the inner query.
D.
The outer query continues evaluating the result set of the inner query until all the values in the result set are
processed.
Explanation:
http://www.techonthenet.com/oracle/exists.php
When you write EXISTS in a where clause, you’re telling the optimizer that you want the outer query to be run first, using each value to fetch a value from the inner query (think: EXISTS = outside to inside).
The EXIST clause says to run the query, stopping as soon as it finds the first match. If it finds a match, it returns true, if not it returns false.