SQL> SET ECHO ON
SQL> SET SERVEROUTPUT ON
SQL> DECLARE
2 a INTEGER;
3 b BOOLEAN;
4 n INTEGER; --this will be our null value.
5 BEGIN
6 a := 2;
7
8 IF NVL((a <> n),true) THEN
9 DBMS_OUTPUT.PUT_LINE('The values are not equal.');
10 ELSE
11 DBMS_OUTPUT.PUT_LINE('The values are equal.');
12 END IF;
13 END;
14 /
The values are not equal.
PL/SQL procedure successfully completed.
SQL>