IS NULL : IS NULL « PL SQL Operators « Oracle PL/SQL Tutorial

1. Oracle PL/SQL Tutorial
2. PL SQL Operators
3. IS NULL

The IS NULL operator is used to test a NULL value.

Variables you declare in a PL/SQL block are also initially null, or have no value.

Variables remain null until your code specifically assigns a value to them.

The Syntax for IS NULL:

the_value IS [NOT] NULL

the_value is a variable, or another expression.

If the value is null, then the IS NULL operator returns true.

You can also reverse the test by using IS NOT NULL.

SQL>
SQL> --Remember to execute: SET SERVEROUTPUT ON
SQL> DECLARE
  2    test  INTEGER;
  3  BEGIN
  4    IF test IS NULL THEN
  5      DBMS_OUTPUT.PUT_LINE('The variable TEST is null.');
  6    END IF;
  7     test := 1;
  8     DBMS_OUTPUT.PUT_LINE('TEST = ' || TO_CHAR(test));
  9     IF test IS NOT NULL THEN
 10       DBMS_OUTPUT.PUT_LINE('The variable TEST is NOT null.');
 11     END IF;
 12  END;
 13  /
The variable TEST is null.
TEST = 1
The variable TEST is NOT null.

PL/SQL procedure successfully completed.

SQL>