I have 2 page items (a, b) and their "Type" is "Number". I create validation on item "a" and validation "Type" is "Function Body (returning Boolean)" and PL/SQL code is
BEGIN
IF NVL(:a, 0) <= NVL(:b, 0) THEN
return true;
ELSE
return false;
END IF;
END;
furthermore i use "Expression" as well where "SQL Expression" is
NVL(:P8_PORD_VALUE, 0) <= NVL(:P8_UBALANCE, 0)
but these are not working properly.