如何消除SQL Server内部联接中的重复项

我将加入3个表机遇、领导、备注

我得到了副本。如何在使用内部联接时避免重复

主表是Opportunity，Notes与Opportunity id进行比较，Notes表中有许多记录具有相同的Opportunity，因此发生重复。现在，我如何在比较表和获取上次更新的注释时避免重复

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先谢谢你

确保不要在此处意外使用笛卡尔积：

from Opportunity O, Notes N

这应该只是

您已在稍后加入Notes表

因此，这里的查询应该不会返回任何重复项：

Select 
     O.oppo_jobid, O.oppo_status,
     cast(N.Note_Note as NCHAR) as Notes 
from dbo.Opportunity O
Inner join dbo.Notes on o.Oppo_OpportunityId = Notes.Note_ForeignId 
Inner join dbo.Lead on o.Oppo_OpportunityId = Lead.Lead_OpportunityID

更新：如果您只需要每个opportunity的最新注释，请使用此查询：

;WITH MostRecent AS
(
    SELECT 
        O.oppo_jobid, O.oppo_status,
        cast(N.Note_Note as NCHAR) as Notes,
        ROW_NUMBER() OVER (PARTITION BY o.Oppo_OpportunityId 
                           ORDER BY n.Note_DateTimeStamp DESC) AS 'RowNum'
    FROM dbo.Opportunity O
    INNER JOIN dbo.Notes on o.Oppo_OpportunityId = Notes.Note_ForeignId 
)
SELECT *
FROM MostRecent
WHERE RowNum = 1

---

确保不要在此处意外地使用笛卡尔积：

from Opportunity O, Notes N

这应该只是

您已在稍后加入Notes表

因此，这里的查询应该不会返回任何重复项：

Select 
     O.oppo_jobid, O.oppo_status,
     cast(N.Note_Note as NCHAR) as Notes 
from dbo.Opportunity O
Inner join dbo.Notes on o.Oppo_OpportunityId = Notes.Note_ForeignId 
Inner join dbo.Lead on o.Oppo_OpportunityId = Lead.Lead_OpportunityID

更新：如果您只需要每个opportunity的最新注释，请使用此查询：

;WITH MostRecent AS
(
    SELECT 
        O.oppo_jobid, O.oppo_status,
        cast(N.Note_Note as NCHAR) as Notes,
        ROW_NUMBER() OVER (PARTITION BY o.Oppo_OpportunityId 
                           ORDER BY n.Note_DateTimeStamp DESC) AS 'RowNum'
    FROM dbo.Opportunity O
    INNER JOIN dbo.Notes on o.Oppo_OpportunityId = Notes.Note_ForeignId 
)
SELECT *
FROM MostRecent
WHERE RowNum = 1

---

+我还想知道如何加入Lead。似乎未使用，可能应替换为存在或完全删除。在notes表中，我有许多记录具有相同的opportunity id。我需要内部联接notes表并检查最近日期的上次更新。选择O.Oppo\U orderstatus作为状态，O.Oppo\U jobid作为jobid，N.Note\U Note作为备注，N.Note\U jobid作为jobid，N.Note\u Updated by as UpdateDate，CastCONVERTDECIMAL10,2，O.Oppo\u currentprice as nvarchar as Total，CastCONVERTDECIMAL10,2，O.Oppo\u currentpmts as nvarchar as Payment，O.Oppo\u branchid as Branch，O.Oppo\u mb as mb，O.Oppo_statuschgdt AS ChangeDate FROM Notes N internal JOIN Opportunity O ON O.Oppo_OpportunityId=N.Note_foreigned where Note_UpdatedBy=Select maxNote_UpdatedBy FROM Notes您不会得到重复的-您只得到几行，因为每个Opportunity都有多个Notes。。。。那么你到底想要什么呢？+1还想知道如何加入Lead。似乎未使用，可能应替换为存在或完全删除。在notes表中，我有许多记录具有相同的opportunity id。我需要内部联接notes表并检查最近日期的上次更新。选择O.Oppo\U orderstatus作为状态，O.Oppo\U jobid作为jobid，N.Note\U Note作为备注，N.Note\U jobid作为jobid，N.Note\u Updated by as UpdateDate，CastCONVERTDECIMAL10,2，O.Oppo\u currentprice as nvarchar as Total，CastCONVERTDECIMAL10,2，O.Oppo\u currentpmts as nvarchar as Payment，O.Oppo\u branchid as Branch，O.Oppo\u mb as mb，O.Oppo_statuschgdt AS ChangeDate FROM Notes N internal JOIN Opportunity O ON O.Oppo_OpportunityId=N.Note_foreigned where Note_UpdatedBy=Select maxNote_UpdatedBy FROM Notes您不会得到重复的-您只得到几行，因为每个Opportunity都有多个Notes。。。。那么你真正想要的是什么呢？？？你的cast表达式castN.Note\u Note as NCHAR将返回一个固定的30个字符长的列，这肯定是你想要的结果吗？加入领导团队的目的是什么？也很容易理解。您的cast表达式castN.Note\u Note as NCHAR将返回一个固定的30个字符长的列，这肯定是您想要的结果吗？加入领导团队的目的是什么？也很容易理解。