EXISTS method

The EXISTS method is used to determine whether a specified element exists in a variable array or nested table.

If the nth element of the collection exists, EXISTS(n) returns TRUE. Otherwise, it returns FALSE. If n is out of bounds, EXISTS returns FALSE without raising the predefined exception SUBSCRIPT_OUTSIDE_LIMIT.

For deleted elements, even if DELETE has reserved a placeholder for them, EXISTS(n) returns FALSE.

Here is an example:

obclient> DECLARE
  TYPE emp_id IS TABLE OF NUMBER;
  n EMP_ID := emp_id(2,4,6,8);
BEGIN
  n.DELETE(2); -- Delete the second element.
  n.TRIM; -- Trim the last element.

  FOR i IN 1..5 LOOP
    IF n.EXISTS(i) THEN
      DBMS_OUTPUT.PUT_LINE('n(' || i || ') = ' || n(i));
    ELSE
      DBMS_OUTPUT.PUT_LINE('n(' || i || ') has no value');
    END IF;
  END LOOP;
END;
/
Query OK, 0 rows affected

n(1) = 2
n(2) has no value
n(3) = 6
n(4) has no value
n(5) has no value

In this example, a nested table is initialized with four elements, the second element is deleted, and the last element is trimmed. The values or status of elements 1 through 6 are then output.