Sum in Access Producing Total Sum and Placing This on Each Row - ms-access-2010

Question

I am trying to create two columns: IntlAir and DomesticAir. I have a Boolean column in my data called International, and IntlAir returns Penalty + SellingFare when International is TRUE, and DomAir returns that sum when International = FALSE.
I would like to show this amount for each DK by Month.
My code is:
SELECT data.PostingMonth, data.DK_Number
, (SELECT sum(data.Penalty + data.SellingFare)
FROM data
WHERE data.International = TRUE) AS IntlAir
, (SELECT sum(data.Penalty + data.SellingFare)
FROM data
WHERE data.International = FALSE) AS DomesticAir
FROM data
GROUP BY data.PostingMonth, data.DK_Number
ORDER BY data.PostingMonth;
However, the output is giving me the total sum across all dks and across all months, and putting this value into every row.
Can someone tell me what I am doing wrong?

Answer 1

Perhaps this is all you need:
SELECT
PostingMonth,
DK_Number,
SUM((Penalty + SellingFare) * IIf(International, 1, 0)) AS IntlAir,
SUM((Penalty + SellingFare) * IIf(International, 0, 1)) AS DomAir
FROM [data]
GROUP BY PostingMonth, DK_Number
For the test data...
PostingMonth DK_Number International Penalty SellingFare
------------ --------- ------------- ------- -----------
1 1 False $10.00 $100.00
1 1 True $20.00 $200.00
2 1 False $30.00 $300.00
1 2 False $40.00 $400.00
1 2 False $50.00 $500.00
1 2 True $60.00 $600.00
...the above query returns
PostingMonth DK_Number IntlAir DomAir
------------ --------- ------- -------
1 1 $220.00 $110.00
1 2 $660.00 $990.00
2 1 $0.00 $330.00

Answer 2

There's a few ways to do that, though the one you chose wasn't one of them
Never sure where access is at in terms of sql but if you create a query that does this and call it queryAirTotal or somesuch
SELECT PostingMonth, DK_Number, International, sum(Penalty + SellingFare) as AirTotal
FROM data GROUP BY PostingMonth,DK_Number,International
That will give your totals by month, dk and type then you can do
Select t1.PostingMonth,t1.DK_Number,t1.AirTotal as IntlAir, t2.Total as DomesticAir
From queryAirTotal t1
Left Join queryAirTotal t2
On t1.PostingMonth = t2.PostingMonth and t1.DK_Number = t2.DK_Number
Where t1.International = TRUE and t2.International = FALSE
Though that will miss out Month/DKs where there was only Domestic air and no International air. You could sort that with a full outer join, which I believe access also struggles with.
You can get round that with a Union
Select t1.PostingMonth,t1.DK_Number,t1.AirTotal as IntlAir, t2.Total as DomesticAir
From queryAirTotal t1
Left Join queryAirTotal t2
On t1.PostingMonth = t2.PostingMonth and t1.DK_Number = t2.DK_Number
Where t1.International = TRUE and t2.International = FALSE
Union
Select t1.PostingMonth,t1.DK_Number,t1.AirTotal as IntlAir, t2.Total as DomesticAir
From queryAirTotal t1
Left Join queryAirTotal t2
On t2.PostingMonth = t1.PostingMonth and t2.DK_Number = t1.DK_Number
Where t1.International = TRUE and t2.International = FALSE