mysql - 一行查询重复计算总和

Question

当记录仅在其中一列(e 或 f)中有数据时，下面的查询有效。但是，如果记录在两列中都有数据，自然会导致 b 和 c 重复计数。那么，我该如何应对呢？

SELECT  a.User1
        , isnull(sum(b.Page_Count),0) AS Count1
        , isnull(sum(c.Page_Count),0) AS Count2
        , isnull(sum(d.Page_Count),0) AS Count3
        , e.Material_Location
        , f.Material_Location
From    TaskUser AS a
    LEFT JOIN PaperMaterial AS b
    ON b.Assigned_To = a.User1
    AND b.Date_Assigned between ('06/11/2014') AND ('06/12/2014')
    LEFT JOIN PaperMaterial AS c
    ON c.Assigned_To = a.User1
    AND c.Date_Assigned between ('06/12/2014') AND ('06/13/2014')
    LEFT JOIN PaperMaterial AS d
    ON d.Assigned_To = a.User1
    AND d.Date_Assigned between ('06/09/2014') AND ('06/14/2014')
    LEFT JOIN PaperMaterial AS e
    ON e.Assigned_To = a.User1
    AND e.Date_Assigned between ('06/11/2014') AND ('06/12/2014')
    LEFT JOIN PaperMaterial AS f
    ON f.Assigned_To = a.User1
    AND f.Date_Assigned between ('06/12/2014') AND ('06/13/2014')
GROUP BY a.User1, e.Material_Location, f.Material_Location
Order By a.User1, e.Material_Location, f.Material_Location

Answer 1

试着把 distinct 放在那里......看起来你是从左连接开始计算 double

SELECT  a.User1
        , isnull(sum(DISTINCT b.Page_Count),0) AS Count1
        , isnull(sum(DISTINCT c.Page_Count),0) AS Count2
        , isnull(sum(DISTINCT d.Page_Count),0) AS Count3
        , e.Material_Location
        , f.Material_Location
From    TaskUser AS a
    LEFT JOIN PaperMaterial AS b
    ON b.Assigned_To = a.User1
    AND b.Date_Assigned between ('06/11/2014') AND ('06/12/2014')
    LEFT JOIN PaperMaterial AS c
    ON c.Assigned_To = a.User1
    AND c.Date_Assigned between ('06/12/2014') AND ('06/13/2014')
    LEFT JOIN PaperMaterial AS d
    ON d.Assigned_To = a.User1
    AND d.Date_Assigned between ('06/09/2014') AND ('06/14/2014')
    LEFT JOIN PaperMaterial AS e
    ON e.Assigned_To = a.User1
    AND e.Date_Assigned between ('06/11/2014') AND ('06/12/2014')
    LEFT JOIN PaperMaterial AS f
    ON f.Assigned_To = a.User1
    AND f.Date_Assigned between ('06/12/2014') AND ('06/13/2014')
GROUP BY a.User1, e.Material_Location, f.Material_Location
Order By a.User1, e.Material_Location, f.Material_Location