用SQL语句,删除掉重复项只保留一条
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用SQL语句,删除掉重复项只保留一条
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
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