sql刪除重複記錄

用SQL語句,刪除掉重複項只保留一條

在幾千條記錄裏,存在着些相同的記錄,如何能用SQL語句,刪除掉重複的呢

一、查找表中多餘的重複記錄，重複記錄是根據單個字段（peopleId）來判斷 

select * from people 

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

二、刪除表中多餘的重複記錄，重複記錄是根據單個字段（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) 

三、查找表中多餘的重複記錄（多個字段） 

select * from vitae a 

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

四、刪除表中多餘的重複記錄（多個字段），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) 

五、查找表中多餘的重複記錄（多個字段），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.消除一個字段的左邊的第一位：

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

7.消除一個字段的右邊的第一位：

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（多個字段），不包含rowid最小的記錄 

update vitae set ispass=-1

where peopleId in (select peopleId from vitae group by peopleId

mysql須要 把查詢出來的結果再 select一下

好比 select * from t id in (select id form (select min(id) id from t group by no having count(no)>1)) )