Basic Oracle Concepts and Programming Question:

NULL is a reserved key word and it stands for two things in PL/SQL:

► NULL is an executable statement, and means doing nothing.
► NULL is a data value, and means no value.

The following sample script shows you examples of using NULL keyword:

DECLARE
next_task CHAR(80);
BEGIN
next_task := NULL; -- NULL value

IF next_task IS NOT NULL THEN
DBMS_OUTPUT.PUT_LINE('I am busy.');
ELSE
DBMS_OUTPUT.PUT_LINE('I am free.');
END IF;

IF next_task IS NULL THEN
NULL; -- NULL statement
ELSE
DBMS_OUTPUT.PUT_LINE('... working on ' || next_task);
END IF;
END;

This script should print this:

I am free.