SQL找出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
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

select 
*

from r_people_report_bak ppp where 1=1
and length(ppp.reporting_period)<=6
and ppp.organization_code  || '_' ||
to_char(to_date(ppp.reporting_period ,'YYYY-mm'),'yyyy') || '-' || to_char(to_date(ppp.reporting_period ,'YYYY-mm'),'mm')
|| '_' || ppp.datilor_all
in (

select pp.organization_code || '_' || pp.aa || '_' || pp.datilor_all from (
select p.people_id,p.organization_code,p.datilor_all,

to_char(to_date(p.reporting_period ,'YYYY-mm'),'yyyy') || '-' || to_char(to_date(p.reporting_period ,'YYYY-mm'),'mm') aa
from r_people_report_bak p 
where  p.reporting_period is not null ) pp
group by pp.aa ,pp.organization_code,pp.datilor_all
having count(1) > 1 )