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SQL>
SQL> -- Effects of nulls on boolean expressions.
SQL> SET SERVEROUTPUT ON
SQL>
SQL> DECLARE
2 a INTEGER;
3 n INTEGER; -- be our null value.
4 BEGIN
5 -- Assign a value to the variable A, but leave N null.
6 a := 2;
7 -- Note that the test for A=N fails.
8 IF a = n THEN
9 DBMS_OUTPUT.PUT_LINE('a = n is true');
10 ELSE
11 DBMS_OUTPUT.PUT_LINE('a = n is not true');
12 END IF;
13 END;
14 /
a = n is not true
PL/SQL procedure successfully completed.
SQL>
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