SQL語句實現刪除重覆記錄並只保留一條

複製** **如下:

delete weibotopics where id in(select max(id) from weibotopics group by weiboid,title h**ing count(*) > 1);

sqwww.cppcns.coml：刪除重複資料，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、查詢表中多餘的重覆記錄，重覆記錄是根據單個字段（peopleid）來判斷

複製** **如下:

select * from people where peopleid in (select peopleid from people group by peopleid h**ing c > 1)

2、刪除表中多餘的重覆記錄，重覆記錄是根據單個字段（peopleid）來判斷，只留有rowid最小的記錄

複製** **如下:

delete from people where   peoplename in (select peoplename    from people group by peoplename程式設計客棧      h**ing count(peoplename) > 1) and   peopleid not in (select min(peopleid) from people group by peoplename     h**ing count(peoplename)>1)

3、查詢表中多餘程式設計客棧的重覆記錄（多個字段）

複製** **如下:

select * from vitae a where (a.peopleid,a.seq) in (select peopleid,seqwww.cppcns.com from vitae group by peopleid,seq h**ing count(*) > 1)

4、刪除表中多餘的重覆記錄（多個字段），只留有rowid最小的記錄

複製** **如下:

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

5、查詢表中多餘的重覆記錄（多個字段），不包含rowid最小的記錄

複製** **如下:

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

6.消除乙個欄位的左邊的第一位：

複製** **如下:

update tablename set [title]=right([title],(len([title])-1)) where title like '村%'

7.消除乙個欄位的右邊的第一位：

複製** **如下:

update tablename set [title]=left([title],(len([title])-1)) where title like '%村'

8.假刪除表中多餘的重覆記錄（多個字段），不包含rowid最小的記錄

複製** **如下:

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

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