Result depending of the result of a function.

[SOS]

Hi
How should I write this double function?

I have 4 colums

1 2 3 4

The colums 3 reveive the result of :

If 1+2 >= 1 then true "A"
and false "B"
AND
If 3=A and 4 = NO
then 3 must be True C and false D

A = Support product , Returnable
B= Non support product Returnable
C= Support product Non returnable
D= Non support product Non returnable.

Any help will be appreciate, we manage inventories and we must update these
code for about 70,000 items.

Thanks in advance

SOS