NVL deals with a boolean expression : Null Value « PL SQL « Oracle PL / SQL

1. Oracle PL / SQL
2. PL SQL
3. Null Value

NVL deals with a boolean expression

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     -- TIP: try this if you want a null value to be considered "not equal".
  8     -- Be careful though, if BOTH A and N are NULL NVL will still return TRUE.
  9     IF NVL((a <> n),true) THEN
 10       DBMS_OUTPUT.PUT_LINE('The values are not equal.');
 11     ELSE
 12       DBMS_OUTPUT.PUT_LINE('The values are equal.');
 13     END IF;
 14     -- TIP: a three-valued IF construct.
 15  END;
 16  /
The values are not equal.

PL/SQL procedure successfully completed.

SQL>

           
       

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