Can a JOIN be used instead of a UNION to obtain the Total Sales from B1?

Question

Hi Everyone,
I am in the midst of writing a report which shows the 'Total Sales', 'Gross Profit', and 'Gross Profit %' by Sales Person. Traditionally I have used a UNION between two result sets to achieve this task. However I am wondering it if is possible to achieve the same outcome with a JOIN as shown below?
SELECT
    T0.SlpCode
    , T0.SalesPerson
    , T0.Branch
    , (T0.TotalSales - T1.TotalSales) AS 'Total Sales'
    , ((T0.TotalSales - T1.TotalSales) - (T0.StockValue + T1.StockValue)) AS 'Gross Profit'
    , CAST(((T0.TotalSales - T1.TotalSales) - (T0.StockValue + T1.StockValue)) / NULLIF((T0.StockValue + T1.StockValue), 0) * 100 AS decimal(15,2)) AS 'Gross Profit %'
    FROM
        /*** SAP - Invoices by Sales Person ***/
        SELECT
        T1.SlpCode
        , T2.SlpName AS 'SalesPerson'
        , T2.U_INE_Branch AS 'Branch'
        , CAST(SUM(T0.LineTotal) AS decimal(15,2)) AS 'TotalSales'
        , CAST(SUM(T0.StockValue) AS decimal(15,2)) AS 'StockValue'
        FROM AU.dbo.INV1 T0
        INNER JOIN AU.dbo.OINV T1 ON T1.DocEntry = T0.DocEntry
        LEFT JOIN AU.dbo.OSLP T2 ON T2.SlpCode = T1.SlpCode
        WHERE T1.DocDate >= '2014-08-01' AND T1.DocDate <= '2014-09-01'
        GROUP BY T1.SlpCode, T2.SlpName, T2.U_INE_Branch
    ) AS T0
    FULL JOIN
        /*** SAP - Credits by Sales Person ***/
        SELECT
        T1.SlpCode
        , T2.SlpName AS 'SalesPerson'
        , T2.U_INE_Branch AS 'Branch'
        , ISNULL(CAST(SUM(T0.LineTotal) AS decimal(15,2)), 0) AS 'TotalSales'
        , ISNULL(CAST(SUM(T0.StockValue) AS decimal(15,2)), 0) AS 'StockValue'
        FROM AU.dbo.RIN1 T0
        INNER JOIN AU.dbo.ORIN T1 ON T1.DocEntry = T0.DocEntry
        LEFT JOIN AU.dbo.OSLP T2 ON T2.SlpCode = T1.SlpCode
        WHERE T1.DocDate >= '2014-08-01' AND T1.DocDate <= '2014-09-01'
        GROUP BY T1.SlpCode, T2.SlpName, T2.U_INE_Branch
    ) AS T1
ON T1.SalesPerson = T0.SalesPerson
Currently I am not getting correct results (which I can do through a UNION), but am instead seeing NULLs scattered throughout, as shown below...
(I have blacked out certain details to keep the company I work for anonymous)
My question is: are NULLs unavoidable in this scenario simply because of the nature of JOINs? I have tried a 'JOIN' rather than a 'FULL JOIN' but instead of seeing all of the Sales People I only see Sales People who do not have NULLs, which looks nice but is not particularly accurate.
Any help and suggestions here will be greatly appreciated.
Kind Regards,
David

Answer 1

Hi David,
You can try something like this:
to avoid null
Type in each field the keyword isnull, IsNull((T0.TotalSales - T1.TotalSales), 0) AS 'Total Sales' 
or something like this
SELECT T0.[SlpCode], T0.[SlpName], (Select Sum(T1.doctotal) from oinv t1 where t1.docdate between '???' and '???' and T0.slpcode = t1.slpcode)  - (Select Sum(T2.doctotal) from orin t2 where t2.docdate between '???' and '???' and T0.slpcode = t2.slpcode) as Sales FROM OSLP T0
Hope it helps
Kind regards,
Augusto