SQL - Sum and Group By returning incorrect sums

Question

So I have the query below which I believe should be working correctly but is returning false values

SELECT 
    Period,
    Sum(Amount) as amount

FROM (
    SELECT
        Period,
        Sum(Amount) Amount
    FROM (
        SELECT a.Period, a.Account, SUM(a.Amount) amount
        FROM LedgerAP a
        WHERE a.Period >= @custPeriodStart AND a.Period <= @custPeriodEnd
        GROUP BY a.Period, a.Account

        UNION
        SELECT b.Period, b.Account, SUM(b.Amount) amount
        FROM LedgerAR b
        WHERE b.Period >= @custPeriodStart AND b.Period <= @custPeriodEnd
        GROUP BY b.Period, b.Account

        UNION
        SELECT c.Period, c.Account, SUM(c.Amount) amount
        FROM LedgerEx c
        WHERE c.Period >= @custPeriodStart AND c.Period <= @custPeriodEnd
        GROUP BY c.Period, c.Account

        UNION
        SELECT d.Period, d.Account, SUM(d.Amount) amount
        FROM LedgerMisc d
        WHERE d.Period >= @custPeriodStart AND d.Period <= @custPeriodEnd
        GROUP BY d.Period, d.Account
    ) src1
    GROUP BY Period, Account
) src2

Group by Period

What I'm getting is:

Period  |  Amount
201501  |  -450.00
201502  |  00
201503  |  00
...     |  ...
201512  |  xxxxxx

What I'm expecting is:

Period  |  Amount
201501  |  1731262
201502  |  774221
201503  |  770845
...     |  ...
201512  |  xxxxxx

In other words SUM() isn't returning the correct values. I know my subquery is correctly returning the values I'm looking for but when I GROUP and SUM the values become very incorrect. I'm dealing with positive and negative amounts but my understanding is SUM() should still work correctly. Any ideas?

Answer 1

in your inner SQL there is a GROUP by Period, Account althoug you are not summing up by period + account but only by period. Please try removinge the acccount in the GROUP BY

SELECT
    Period,
    Sum(amount1) Amount
FROM (
    SELECT a.Period, a.Account, SUM(a.Amount) amount1
    FROM LedgerAP a
    WHERE a.Period >= @custPeriodStart AND a.Period <= @custPeriodEnd
    GROUP BY a.Period, a.Account

    UNION
    SELECT b.Period, b.Account, SUM(b.Amount) amount1
    FROM LedgerAR b
    WHERE b.Period >= @custPeriodStart AND b.Period <= @custPeriodEnd
    GROUP BY b.Period, b.Account

    UNION
    SELECT c.Period, c.Account, SUM(c.Amount) amount1
    FROM LedgerEx c
    WHERE c.Period >= @custPeriodStart AND c.Period <= @custPeriodEnd
    GROUP BY c.Period, c.Account

    UNION
    SELECT d.Period, d.Account, SUM(d.Amount) amount1
    FROM LedgerMisc d
    WHERE d.Period >= @custPeriodStart AND d.Period <= @custPeriodEnd
    GROUP BY d.Period, d.Account
) src1
GROUP BY Period