Help with validation expression

Question

I could really use some help. The following validation item works. It keeps new records from being submitted when the p1_units field is greater than 10.
if v('p1_units') <= 10 then
return null;
else
return 'test';
end if;
This is not what I want though. What I want is to use the following in place of where I have the 10.
select s1 - s2 from
(select sum(units) s1 from units_avail where trunc(add_date) <= trunc(sysdate) and model = '56478') t1,
(select sum(units) s2 from orders where model = '56478') t2
This sql statement is used else where in the application and it returns the current count of unit available by summing of the total of all orders and subtracting that from the total of all inventory receipts.
Thanks in advance.

Answer 1

Hi,
If I understood your post correctly this PL/SQL procedure would help:
DECLARE
v_number NUMBER(5);--select precision and scale according to your task
BEGIN
select s1 - s2 into v_number
from
(select sum(units) s1 from units_avail
where trunc(add_date) <= trunc(sysdate) and model = '56478') t1,
(select sum(units) s2 from orders where model = '56478') t2;
if v('p1_units') <= v_number then
return null;
else
return 'test';
end if;
END;
Val