[英]Select statement with result even if there isn't in the db
我有此表,其中包含我對特定客戶訂單的所有附件,我只想選擇一種附件,但是即使沒有附件,我也希望看到該行。 有辦法嗎?
我試過了,但是沒有用:
SELECT
Comm.No_Com,
CASE WHEN Attachement.EntityID IS NULL OR Attachement.ATS_CategoryOfAttachmentCode='DESSIN'
THEN Attachement.FileName
ELSE ' '
END AS Dessin
FROM Comm
INNER JOIN Attachement
ON Comm.COH_Id=Attachement.EntityID
使用LEFT OUTER JOIN代替INNER JOIN。
SELECT
Comm.No_Com,
CASE WHEN Attachement.EntityID IS NULL OR Attachement.ATS_CategoryOfAttachmentCode='DESSIN'
THEN Attachement.FileName
ELSE ' '
END AS Dessin
FROM Comm
LEFT OUTER JOIN Attachement
ON Comm.COH_Id=Attachement.EntityID AND Attachment.Kind = 'DesiredKind'
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