Perform a function after union of two tables - sql

Question

I have two tables that I want to union together then perform some math functions on the combined table.
I know how to do the math for each separate table, but throwing in a union table to go off of is out of my league.
Here's the math for one table using column header "UnitsReceived" and "AsnPsUnits"
The other table would have headers: "cUnitsReceived" and "cAsnPsUnits"
select VendName,
1-abs(((cast(sum(UnitsReceived) as decimal(5,0))) - (cast(sum(AsnPsUnits) as decimal(5,0)))) /(cast(sum(AsnPsUnits) as decimal(5,0)))) as ASNpsAcc
from VenTest2
where ID<20
group by VendName
How would I perform this function after the union of two tables?

Answer 1

You'll need to get the unioned tables into some table object before performing your function. This could be done using:
A Common Table Expression
with cte as (
select ID, VALUE from A
union all
select ID, VALUE from B
)
select
*
,myfunction(VALUE) as MyFunctionResult
from
cte
A temp table
select ID, VALUE into #myTempTable from A
insert into #myTempTable select ID, VALUE from B
select
*
,myfunction(VALUE) as MyFunctionResult
from
#myTempTable
A table variable
declare #myTableVariable table (ID int, VALUE decimal)
insert into #myTableVariable
select ID, VALUE from A
union all
select ID, VALUE from B
select
*
,myfunction(VALUE) as MyFunctionResult
from
#myTableVariable
A sub query
select
*
,myfunction(VALUE) as MyFunctionResult
from
(
select ID, VALUE from A
union all
select ID, VALUE from B
) mySubQuery

Answer 2

This will help with the subq being the union
select VendName,
1-abs(((cast(sum(UnitsReceived) as decimal(5,0))) - (cast(sum(AsnPsUnits) as decimal(5,0)))) /(cast(sum(AsnPsUnits) as decimal(5,0)))) as ASNpsAcc
from
(
select ID, UnitsReceived, AsnPsUnits from VenTest2 where ID<20
union
select ID1, UnitsReceived1, AsnPsUnits1 from VenTest1
)a
group by VendName

Answer 3

This is not the way, brothers:
select VendName,
1-abs(((cast(sum(UnitsReceived) as decimal(10,2))) - (cast(sum(AsnPsUnits) as decimal(10,2)))) /(cast(sum(AsnPsUnits) as decimal(10,2)))) as ASNpsAcc
from VenTest2
where ID<10
group by VendName
union
select cVendName,
1-abs(((cast(sum(cUnitsReceived) as decimal(10,2))) - (cast(sum(casnpsunits) as decimal(10,2)))) /(cast(sum(cAsnPsUnits) as decimal(10,2)))) as ASNpsAcc
from CTest
where id <10
group by cvendname