多线程实现的四种方式 怎样查询数据库中重复的数据?
怎样查询数据库中重复的数据?
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 peoplewhere 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 peopleId in (select peopleId from people group by peopleId having count (peopleId) > 1)and rowid not in (select min(rowid) from people group by peopleId having count(peopleId )>1)
3、查找表中多余的重复记录(多个字段)
select * from vitae awhere (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having
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