使用INNER JOIN獲取DISTINCT記錄

Question

我在多個表上都有follwong查詢

SELECT DISTINCT b.BoxBarcode as [Box Barcode], (select case when  b.ImagesCount IS NULL
        then 0 
        else  b.ImagesCount end) as [Total Images], s.StageName as [Current   Stage] ,d.DocuementTypeName as [Document Type],
        u.UserName as [Start User],uu.UserName as [Finished User]

FROM [dbo].[Operations] o
    inner join dbo.LKUP_Stages s on 
        o.stageid=s.id
    inner join dbo.LKUP_Users u on
        u.id=o.startuserid
    left join dbo.LKUP_Users uu on
        uu.id=o.FinishedUserID
    inner join boxes b on
        b.id=o.boxid
    inner join LKUP_DocumentTypes d on
        d.ID = b.DocTypeID 

where b.IsExportFinished = 0

當我從IsExportFinished = 0表中選擇IsExportFinished = 0的計數時，我得到了Count 42條記錄，當我運行上述qoury時，我得到了71條記錄，我只希望檢索Boxes表中的42條記錄。

Answer 1

您正在進行一對多聯接，即至少一個表具有匹配聯接條件的多行。

第一步是查找給出“重復項”的表。

完成后，您可以通過向聯接添加其他條件來解決問題。 我猜測在Operations表中會多次出現相同的boxid 。 如果是這種情況，則需要確定要選擇的“ Operation行，然后相應地更新SQL。

Answer 2

試試這個-

SELECT
      Box_Barcode = b.BoxBarcode
    , Total_Images = ISNULL(b.ImagesCount, 0)
    , Current_Stage = s.StageName
    , Document_Type = d.DocuementTypeName
    , Start_User = u.UserName
    , Finished_User = uu.UserName
FROM (
    SELECT DISTINCT 
          o.stageid
        , o.boxid
        , o.startuserid
        , o.FinishedUserID
    FROM dbo.[Operations]
) o
JOIN dbo.LKUP_Stages s ON o.stageid = s.id
JOIN dbo.boxes b ON b.id = o.boxid
JOIN dbo.LKUP_DocumentTypes d ON d.id = b.DocTypeID
JOIN dbo.LKUP_Users u ON u.id = o.startuserid
LEFT JOIN dbo.LKUP_Users uu ON uu.id = o.FinishedUserID
WHERE b.IsExportFinished = 0

Answer 3

我想如果您將LEFT JOIN更改為INNER JOIN，您將獲得42條記錄。