SQL服務器 - 不同的WHERE的條款，以不同的列

Question

我需要指定不同的，其中的條款，以不同的列，例如，我的「PrinterCounter.EndPagesColor」和「PrinterCounter.EndPagesMono」我想用這個地方：

WHERE 
    PrinterCounter.ReadTime >= '01/07/2017 00:00:01' 
    AND PrinterCounter.ReadTime <= '31/07/2017 23:59:59' 
    AND Printer.WasRemoved = 0 
    AND ClientId = 6 
    AND SubClientId = 752 
ORDER BY 
    PrinterCounter.ReadTime DESC 

但對於 「PrinterCounter.StartPagesColor」 和 「PrinterCounter.StartPagesMono」 我想這一個：

WHERE 
    PrinterCounter.ReadTime >= '01/07/2017 00:00:01' AND 
    PrinterCounter.ReadTime <= '31/07/2017 23:59:59' AND 
    Printer.WasRemoved = 0 AND 
    ClientId = 6 AND 
    SubClientId = 752 
ORDER BY 
    PrinterCounter.ReadTime ASC 

下面是完整的代碼：

SELECT DISTINCT 
    Printer.[PrinterId], 
    Printer.[PlaceId], 
    PrinterCounter.ReadTime, 
    PrinterCounter.EndPagesColor, 
    PrinterCounter.EndPagesMono, 
    PrinterCounter.StartPagesColor, 
    PrinterCounter.StartPagesMono 
FROM  
    [~client_database~].[dbo].[Printers] AS Printer 
JOIN 
    [~system_database~].[dbo].[PrinterCounter] AS PrinterCounter ON PrinterCounter.PrinterId = Printer.PrinterId 
WHERE 
    PrinterCounter.ReadTime >= '01/07/2017 00:00:01' 
    AND PrinterCounter.ReadTime <= '31/07/2017 23:59:59' 
    AND Printer.WasRemoved = 0 
    AND ClientId = 6 
    AND SubClientId = 752 
ORDER BY 
    PrinterCounter.ReadTime ASC 

我會爲你弄清楚，每臺打印機在一天開始時有一個計數器，一天在結束時，產量將減去開始。

每個客戶有幾臺打印機，我必須在提供的時間內收集每臺打印機的產量。

該連接是爲了確保SQL僅返回帶有計數器的打印機。

---

這是一個想：

SELECT 
DISTINCT 
    Printer.PrinterId 
    ,Printer.PlaceId 
    ,PrinterCounter.ReadTime 
    ,(
     SELECT TOP 1 
      EndPagesMono 
     FROM 
      [system_mfpm].[dbo].[PrinterCounter] 
     WHERE 
      PrinterCounter.ReadTime >= '01/07/2017 00:00:01' AND PrinterCounter.ReadTime <= '31/07/2017 23:59:59' 
      AND PrinterCounter.ClientId = 6 
      AND PrinterCounter.SubClientId = 752 
      AND PrinterCounter.PrinterId = Printer.PrinterId 
     ORDER BY PrinterCounter.ReadTime DESC 
    )-(
     SELECT TOP 1 
      StartPagesMono 
     FROM 
      [system_mfpm].[dbo].[PrinterCounter] 
     WHERE 
      PrinterCounter.ReadTime >= '01/07/2017 00:00:01' AND PrinterCounter.ReadTime <= '31/07/2017 23:59:59' 
      AND PrinterCounter.ClientId = 6 
      AND PrinterCounter.SubClientId = 752 
      AND PrinterCounter.PrinterId = Printer.PrinterId 
     ORDER BY PrinterCounter.ReadTime ASC 
    ) AS Mono 
    ,(
     SELECT TOP 1 
      EndPagesColor 
     FROM 
      [system_mfpm].[dbo].[PrinterCounter] 
     WHERE 
      PrinterCounter.ReadTime >= '01/07/2017 00:00:01' AND PrinterCounter.ReadTime <= '31/07/2017 23:59:59' 
      AND PrinterCounter.ClientId = 6 
      AND PrinterCounter.SubClientId = 752 
      AND PrinterCounter.PrinterId = Printer.PrinterId 
     ORDER BY PrinterCounter.ReadTime DESC 
    )-(
     SELECT TOP 1 
      StartPagesColor 
     FROM 
      [system_mfpm].[dbo].[PrinterCounter] 
     WHERE 
      PrinterCounter.ReadTime >= '01/07/2017 00:00:01' AND PrinterCounter.ReadTime <= '31/07/2017 23:59:59' 
      AND PrinterCounter.ClientId = 6 
      AND PrinterCounter.SubClientId = 752 
      AND PrinterCounter.PrinterId = Printer.PrinterId 
     ORDER BY PrinterCounter.ReadTime ASC 
    ) AS Color               
    FROM [client_lfn_MTUXNJCZMJQA].[dbo].[Printers] AS Printer 
    JOIN [system_mfpm].[dbo].[PrinterCounter] AS PrinterCounter ON PrinterCounter.PrinterId = Printer.PrinterId 
    WHERE Printer.WasRemoved = 0 

，但我敢肯定這是一個不好的做法，它可以提高

Answer 1

好吧，我想我理解你，雖然我」我不知道這是怎麼回事。

如果PrinterCounter.EndPagesColor，PrinterCounter.EndPagesMono，printerCounter.StartPagesColor，PrinterCounter.StartPagesMono是你想，那麼你可以使用條件的聚集與CASE EXPRESSION新列，它會是這個樣子：

SELECT 
    Printer.[PrinterId], 
    Printer.[PlaceId], 
    PrinterCounter.ReadTime, 
    MAX(CASE WHEN <Your first conditions> THEN PrinterCounter.PagesColor END) as StartPagesColor, 
    MAX(CASE WHEN <Your first conditions> THEN PrinterCounter.PagesMono END) as StartMonoColor,  
    MAX(CASE WHEN <Your second conditions> THEN PrinterCounter.PagesColor END) as EndPagesColor, 
    MAX(CASE WHEN <Your second conditions> THEN PrinterCounter.PagesMono END) as EndMonoColor  
FROM ... // rest of query 
GROUP BY Printer.[PrinterId], 
     Printer.[PlaceId], 
     PrinterCounter.ReadTime 

雖然我覺得你還需要從選擇列表中刪除ReadTime列。