【轉】SQL重複資料刪除記錄,只保留其中一條

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SQL：重複資料刪除資料，只保留一條用SQL語句,刪除掉重複項只保留一條在幾千條記錄裡,存在著些相同的記錄,如何能用SQL語句,刪除掉重複的呢

 1、尋找表中多餘的重複記錄，重複記錄是根據單個欄位（peopleId）來判斷

 select * from people where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1)

2、刪除表中多餘的重複記錄，重複記錄是根據單個欄位（peopleId）來判斷，只留有rowid最小的記錄

delete from people where   peopleName in (select peopleName    from people group by peopleName      having count(peopleName) > 1) and   peopleId not in (select min(peopleId) from people group by peopleName     having count(peopleName)>1)

3、尋找表中多餘的重複記錄（多個欄位）

select * from vitae a where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)

4、刪除表中多餘的重複記錄（多個欄位），只留有rowid最小的記錄

delete from vitae a where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1) and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1)

5、尋找表中多餘的重複記錄（多個欄位），不包含rowid最小的記錄 

select * from vitae a where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1) and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1)  

6.消除一個欄位的左邊的第一位：

update tableName set [Title]=Right([Title],(len([Title])-1)) where Title like ‘村%‘

7.消除一個欄位的右邊的第一位：

update tableName set [Title]=left([Title],(len([Title])-1)) where Title like ‘%村‘

8.假刪除表中多餘的重複記錄（多個欄位），不包含rowid最小的記錄

 update vitae set ispass=-1 where peopleId in (select peopleId from vitae group by peopleId,seq having count(*) > 1) and seq in （select seq from vitae group by peopleId,seq having count(*) > 1） and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1)    

 

本文轉自：http://www.cnblogs.com/huangw/archive/2012/06/04/2534676.html

【轉】SQL重複資料刪除記錄,只保留其中一條