Question

SELECT MID, FAD.FirstOpenedDate ,LCD.LastCloseDate
FROM mwMaster.dbo.Merchant M
JOIN        (
            SELECT MerchID, MIN(moddate) AS FirstOpenedDate
            FROM mwMaster.dbo.MerchantStatusHistory
            GROUP BY MerchID
            )   FAD ON FAD.MerchID = M.MerchID 
LEFT JOIN   (
            SELECT MerchID, MAX(moddate) AS LastCloseDate
            FROM mwMaster.dbo.MerchantStatusHistory
            GROUP BY MerchID
            )   LCD ON LCD.MerchID = M.MerchID
JOIN        (
            SELECT merchid ,avg(Transactions) ,avg(Profit) 
            FROM mwMaster.dbo.ResidualSummary RS
            WHERE RS.Date_Processed < LCD.LastCloseDate
            GROUP BY Merchid    
            )   R ON R.MerchID = M.MerchID

我无法执行以下加入。我之前遇到过这个问题并使用临时表但想知道我做错了什么。基本上不起作用的线是倒数第三。 “＆lt; LCD.LastClostDate”表示无法绑定。是否可以使用我在上面的嵌套查询中创建的LCD值（在该查询中我以类似的方式使用M表，但我没遇到任何问题）？我在想，因为LCD表是动态创建的，它不能在嵌套查询中使用，但这只是我的猜测。

有什么想法吗？

另一方面，我也看到人们使用CROSS和OVER。不熟悉它是如何工作的，但可能适用于此处？

Answer 1

我认为虽然没有经过测试，但您可以在SQL 2005 +中将JOIN更改为CROSS APPLY

SELECT MID, FAD.FirstOpenedDate ,LCD.LastCloseDate
FROM mwMaster.dbo.Merchant M
JOIN        (
            SELECT MerchID, MIN(moddate) AS FirstOpenedDate
            FROM mwMaster.dbo.MerchantStatusHistory
            GROUP BY MerchID
            )   FAD ON FAD.MerchID = M.MerchID 
LEFT JOIN   (
            SELECT MerchID, MAX(moddate) AS LastCloseDate
            FROM mwMaster.dbo.MerchantStatusHistory
            GROUP BY MerchID
            )   LCD ON LCD.MerchID = M.MerchID
CROSS APPLY(
        SELECT merchid ,avg(Transactions) ,avg(Profit) 
        FROM mwMaster.dbo.ResidualSummary RS
        WHERE RS.Date_Processed < LCD.LastCloseDate
        GROUP BY Merchid    
        )   R ON R.MerchID = M.MerchID

但使用CTE可能更容易

 WITH LCD AS (SELECT MerchID, MAX(moddate) AS LastCloseDate
        FROM mwMaster.dbo.MerchantStatusHistory
        GROUP BY MerchID),
  R AS (
              SELECT merchid ,avg(Transactions) ,avg(Profit) 
              FROM mwMaster.dbo.ResidualSummary RS
                   INNER JOIN LCD on 
                   LCD.MERCHID = RS.MERCHID
              WHERE RS.Date_Processed < LCD.LastCloseDate
              GROUP BY Merchid    
            )

SELECT MID, FAD.FirstOpenedDate ,LCD.LastCloseDate
FROM mwMaster.dbo.Merchant M
JOIN        (
            SELECT MerchID, MIN(moddate) AS FirstOpenedDate
            FROM mwMaster.dbo.MerchantStatusHistory
            GROUP BY MerchID
            )   FAD ON FAD.MerchID = M.MerchID 
LEFT JOIN LCD ON LCD.MerchID = M.MerchID
LEFT JOIN R ON R.MerchID = M.MerchID

Answer 2

如果没有您的数据，我无法对此进行测试，但这是您可以采用的一种方式：

SELECT MID,
       MIN(moddate) OVER (PARTITION BY MerchID) as FirstOpenedDate,
       MAX(moddate) OVER (PARTITION BY MerchID) as LastCloseDate
FROM mwMaster.dbo.Merchant
HAVING DateProcessed < LastCloseDate

在SQL中连接表时出现问题

2 个答案: