带左连接的SQL连接

当执行下面的sql查询时，并没有按预期输出。请纠正我

SELECT              
COALESCE(NULLIF(b1.ShortCode,NULL)+'|'+ NULLIF(b2.ShortCode,NULL)+'|'+ 
NULLIF(b3.ShortCode,NULL)+'|'+ 
NULLIF(b4.ShortCode,NULL),NULLIF(b5.ShortCode,NULL))as Result
FROM tbl_PropertyDetails                                
LEFT JOIN tbl_FamilyMember b1 ON tbl_PropertyDetails.Member1ID = b1.FMID
LEFT JOIN tbl_FamilyMember b2 ON tbl_PropertyDetails.Member2ID = b2.FMID
LEFT JOIN tbl_FamilyMember b3 ON tbl_PropertyDetails.Member3ID = b3.FMID
LEFT JOIN tbl_FamilyMember b4 ON tbl_PropertyDetails.Member4ID = b4.FMID
LEFT JOIN tbl_FamilyMember b5 ON tbl_PropertyDetails.Member5ID = b5.FMID
[enter image description here][1]

试试这个：

SELECT  COALESCE(b1.ShortCode, '') + '|' + COALESCE(b2.ShortCode, '') + '|'
        + COALESCE(b3.ShortCode, '') + '|' + COALESCE(b4.ShortCode, '') ,
        COALESCE(b5.ShortCode, '') AS Result
FROM    tbl_PropertyDetails
        LEFT JOIN tbl_FamilyMember b1 ON tbl_PropertyDetails.Member1ID = b1.FMID
        LEFT JOIN tbl_FamilyMember b2 ON tbl_PropertyDetails.Member2ID = b2.FMID
        LEFT JOIN tbl_FamilyMember b3 ON tbl_PropertyDetails.Member3ID = b3.FMID
        LEFT JOIN tbl_FamilyMember b4 ON tbl_PropertyDetails.Member4ID = b4.FMID
        LEFT JOIN tbl_FamilyMember b5 ON tbl_PropertyDetails.Member5ID = b5.FMID

---

您可能需要相当于

CONCAT\u WS（）

。将

|

仅放在实际值之间。如果是：

SELECT STUFF( COALESCE('|' + b1.ShortCode, '') + 
              COALESCE('|' + b2.ShortCode, '') + 
              COALESCE('|' + b3.ShortCode, '') + 
              COALESCE('|' + b4.ShortCode, '') + 
              COALESCE('|' + b5.ShortCode, ''),
              1, 1, '') as Result
FROM tbl_PropertyDetails LEFT JOIN
     tbl_FamilyMember b1
     ON tbl_PropertyDetails.Member1ID = b1.FMID LEFT JOIN
     tbl_FamilyMember b2
     ON tbl_PropertyDetails.Member2ID = b2.FMID LEFT JOIN
     tbl_FamilyMember b3
     ON tbl_PropertyDetails.Member3ID = b3.FMID LEFT JOIN
     tbl_FamilyMember b4
     ON tbl_PropertyDetails.Member4ID = b4.FMID LEFT JOIN
     tbl_FamilyMember b5
     ON tbl_PropertyDetails.Member5ID = b5.FMID;

---

你得到了什么样的输出？你希望它是什么样的输出？否则我们无法解决这个问题。请告诉我们实际结果是什么，您想要什么结果，以及表描述。至少您需要描述预期的输出，以及它与您得到的结果有何不同。string concat null=>null。

NULLIF（x，null）

是冗余的-只有当

x

为

NULL

时，它才会返回

NULL

-因此，只要使用

NULL（x，NULL）

即可