SQL语句实现删除重复记录并只保留一条
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2022-06-24 22:49:46
复制代码 代码如下:
delete weibotopics where id in(select max(id) from weibotopics group by we...
复制代码 代码如下:
delete weibotopics where id in(select max(id) from weibotopics group by weiboid,title having count(*) > 1);
sql：删除重复数据，只保留一条用sql语句,删除掉重复项只保留一条在几千条记录里,存在着些相同的记录,如何能用sql语句,删除掉重复的呢
1、查找表中多余的重复记录，重复记录是根据单个字段（peopleid）来判断
复制代码 代码如下:
select * from people where peopleid in (select peopleid from people group by peopleid having count(peopleid) > 1)
2、删除表中多余的重复记录，重复记录是根据单个字段（peopleid）来判断，只留有rowid最小的记录
复制代码 代码如下:
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、查找表中多余的重复记录（多个字段）
复制代码 代码如下:
select * from vitae a where (a.peopleid,a.seq) in (select peopleid,seq from vitae group by peopleid,seq having count(*) > 1)
4、删除表中多余的重复记录（多个字段），只留有rowid最小的记录
复制代码 代码如下:
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、查找表中多余的重复记录（多个字段），不包含rowid最小的记录
复制代码 代码如下:
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.消除一个字段的左边的第一位：
复制代码 代码如下:
update tablename set [title]=right([title],(len([title])-1)) where title like '村%'
7.消除一个字段的右边的第一位：
复制代码 代码如下:
update tablename set [title]=left([title],(len([title])-1)) where title like '%村'
8.假删除表中多余的重复记录（多个字段），不包含rowid最小的记录
复制代码 代码如下:
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)