mysql重复记录的查询删除方法
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 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 C_Yyt
WHERE (Elon IN (SELECT elon FROM C_Yyt GROUP BY elon, wd HAVING COUNT(*) > 1)) AND (wd IN (SELECT wd FROM C_Yyt GROUP BY elon, wd 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、删除重复数据
1、将重复数据中的最小的id都找出来,并插入到一个临时表中;
2、再通过表关联删除掉重复的数据;
INSERT into line_pass_init select min(id) from tt_rps_line_passzone_info_init group by plan_send_batch_dt,line_id,passid,order_flag having count(*)>1
#性能低
DELETE from tt_rps_line_passzone_info_init where id not exists (select id from line_pass_init);
#性能高
delete from tt_rps_line_passzone_info_init a where not exists(select 1 from line_pass_stor_init b where a.id=b.id);