EXISTS method

You can use the EXISTS function to check whether a specified element exists in a variable array or nested table.

EXISTS(n) returns TRUE if the nth element exists in the collection, and returns FALSE if otherwise. If n exceeds the valid range, EXISTS returns FALSE without causing the predefined SUBSCRIPT_OUTSIDE_LIMIT exception.

EXISTS(n) returns FALSE for deleted elements, even if the DELETE method retains placeholders for them.

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

The preceding example initializes and assigns values to four elements in a nested table, deletes the second element, trims the last element, and outputs the values or states of elements 1 to 6.