Equal and UnEqual

Sometimes you have to check the Equality of two variables.

Writing "IF A = B THEN" is not the solution for all cases. If one variable is NULL the whole statement is NULL and NULL becomes FALSE in an IF-Statement. So you have to work with a different technique:

FUNCTION Equal (P_String1  IN VARCHAR2,
                P_String2  IN VARCHAR2) RETURN BOOLEAN IS
BEGIN
  IF P_String1 = P_String2
  OR (P_String1 IS NULL AND P_String2 IS NULL) THEN
    RETURN (TRUE);
  ELSE
    RETURN (FALSE);
  END IF;
END;

FUNCTION UnEqual (P_String1  IN VARCHAR2,
                  P_String2  IN VARCHAR2) RETURN BOOLEAN IS
BEGIN
  IF P_String1 != P_String2
  OR (    P_String1 IS     NULL
      AND P_String2 IS NOT NULL)
  OR (    P_String1 IS NOT NULL
      AND P_String2 IS     NULL) THEN
    RETURN (TRUE);
  ELSE
    RETURN (FALSE);
  END IF;
END;

Now you can easily use Equal and UnEqual

IF UnEqual (Var1, Var2) THEN
  -- do something
ELSE
  -- do something different
END IF;

try it