| 标题 | sql删除重复数据只保留一条 |
| 内容 | 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 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 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) 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 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 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： 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： 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 update vitae set ispass=-1 where peopleid in (select peopleid from vitae group by peopleid alter table mytable drop index mdl_tag_use_ix;//mdl_tag_use_ix是上表查出的索引名，key_name |
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