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--測試資料
/*-----------------------------
select*fromtt
-----------------------------*/
id         pid        
----------------------
1          1
1          1
2          2
3          3
3          3
3          3

（所影響的行數為6行）

首先，如何查詢table中有重複記錄
select*,count(1)asrownum
fromtt
groupbyid,pid
havingcount(1)>1
id         pid        rownum     
---------------------------------
1          1          2
3          3          3

（所影響的行數為2行）

方法一:使用distinct和臨時表
ifobject_id('tempdb..#tmp')isnotnull
droptable#tmp
selectdistinct*into#tmpfromtt
truncatetablett
insertintottselect*from#tmp

方法二:新增標識列
altertablettaddNewIDintidentity(1,1)
go 
deletefromtt whereexists(select1fromttawhere a.newid>tt.newidandtt.id=a.idandtt.pid=a.pid)
go
altertablettdropcolumnNewID
go

--測試結果
/*-----------------------------
select*fromtt
-----------------------------*/
id         pid        
----------------------
1          1
2          2
3          3

（所影響的行數為3行）

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