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我有一个不返回我正在寻找的结果的子查询。在最后一个子查询中，我有 3 个部分在我的条件下没有日期范围的订单计数，并且它们没有返回结果为 0。相反，我丢失了这些部分的所有其他数据。我确信有更好的方法来查询数据，所以这是我的查询。

    SELECT b.Part, b.Last_12_Mo, b.Last_6_Mo,
       COUNT(sd.SBINV) AS Order_Count
  FROM (
        SELECT a.Part, a.Last_12_Mo,
               ISNULL(SUM(sd.SBQSHP), 0) AS Last_6_Mo
          FROM (
                SELECT t3.Part, ISNULL(SUM(sd.SBQSHP),0) AS Last_12_Mo
                  FROM Top300 AS t3
                  LEFT JOIN SalesData AS sd 
                    ON t3.Part   = sd.SBITEM
                   AND sd.SBINDT > '20120315'
                 GROUP BY t3.Part, sd.SBLOC
                ) AS a 
          LEFT JOIN SalesData AS sd
            ON a.Part       = sd.SBITEM
           AND sd.SBINDT    > '20121015'
         GROUP BY a.Part, a.Last_12_Mo
        ) AS b 
  LEFT JOIN SalesData AS sd
    ON b.Part       = sd.SBITEM
   AND sd.SBINDT    > '20130110'
 GROUP BY b.Part, b.Last_12_Mo, b.Last_6_Mo
 ORDER BY b.Part
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1 回答 1

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干得好。这应该这样做。

  • 由于您始终希望 Top300 中的所有项目无论其销售数据如何，您始终必须将每个子查询的结果保留在 LEFT JOIN 的 LEFT 侧。
  • 您可以将 NULL SUM 聚合解析为零
  • 日期过滤器需要在 JOIN 中，因为您不想限制未加入的 Top300 项。如果将它们放在 WHERE 子句中，那么它将排除不与销售数据连接的 Top300 项目，因为这些记录的日期将为 NULL。

首先设置测试表和数据

    IF OBJECT_ID('Top300', 'U') IS NOT NULL DROP TABLE Top300;
    GO
    IF OBJECT_ID('SalesData', 'U') IS NOT NULL DROP TABLE SalesData;
    GO
    CREATE TABLE Top300 (
        Part  varchar(10)
    )
    GO
    CREATE TABLE SalesData (
        SBITEM  varchar(10)
       ,SBQSHP  int
       ,SBINV   int
       ,SBINDT  int
    )
    GO

    INSERT Top300
    SELECT A.*
      FROM (
            SELECT * FROM Top300 WHERE 1=2
            UNION ALL SELECT 'Widget1'
            UNION ALL SELECT 'Widget2'
            UNION ALL SELECT 'Widget3'
            UNION ALL SELECT 'Widget4'
            UNION ALL SELECT 'Widget5'
            UNION ALL SELECT 'Widget6'
           ) A

    INSERT SalesData
    SELECT A.*
      FROM (
            SELECT * FROM SalesData WHERE 1=2
            UNION ALL SELECT 'Widget1', 100, 1000, '20120316'
            UNION ALL SELECT 'Widget2', 100, 1000, '20120316'

            UNION ALL SELECT 'Widget3', 100, 1000, '20121016'
            UNION ALL SELECT 'Widget4', 100, 1000, '20121016'
            UNION ALL SELECT 'Widget5', 100, 1000, '20121016'
           ) A

现在让我们运行原始查询的更正版本

    SELECT b.Part, b.Last_12_Mo, b.Last_6_Mo,
           COUNT(sd.SBINV) AS Order_Count
      FROM (
            SELECT a.Part, a.Last_12_Mo,
                   ISNULL(SUM(sd.SBQSHP), 0) AS Last_6_Mo
              FROM (
                    SELECT t3.Part, ISNULL(SUM(sd.SBQSHP),0) AS Last_12_Mo
                      FROM Top300 AS t3
                      LEFT JOIN SalesData AS sd 
                        ON t3.Part   = sd.SBITEM
                       AND sd.SBINDT > '20120315'
                     GROUP BY t3.Part
                    ) AS a 
              LEFT JOIN SalesData AS sd
                ON a.Part       = sd.SBITEM
               AND sd.SBINDT    > '20121015'
             GROUP BY a.Part, a.Last_12_Mo
            ) AS b 
      LEFT JOIN SalesData AS sd
        ON b.Part       = sd.SBITEM
       AND sd.SBINDT    > '20130110'
     GROUP BY b.Part, b.Last_12_Mo, b.Last_6_Mo
     ORDER BY b.Part

最后，让我们运行一个更简单、更优化的查询，生成相同的结果

    SELECT b.Part
          ,SUM(CASE WHEN sd.SBINDT > '20120315' THEN sd.SBQSHP ELSE 0 END) as [Last_12_Mo]
          ,SUM(CASE WHEN sd.SBINDT > '20121015' THEN sd.SBQSHP ELSE 0 END) as [Last_6_Mo]
          ,SUM(CASE WHEN sd.SBINDT > '20130110' THEN 1 ELSE 0 END) as [Order_Count]
      FROM Top300 b
      LEFT JOIN SalesData AS sd
        ON b.Part       = sd.SBITEM
       AND sd.SBINDT    > '20120315'
     GROUP BY b.Part
     ORDER BY b.Part
于 2013-03-15T17:13:42.443 回答