SQL重复记录查询

Posted 2020-10-27 zhouxinfei

sql语句：
1.Select COUNT(distinct ann_id) from dmdb.t_bond_ann_att_info where last_update_time >= ‘2018-03-09 14:00:00‘;

2.Select COUNT(id) from dmdb.t_bond_ann_info where create_time >= ‘2018-03-09 14:00:00‘;

3.Select a.* from
dmdb.t_bond_ann_info a
where a.id not in (
select ann_id from  t_bond_ann_att_info
  where last_update_time >= ‘2018-03-09 14:00:00‘   
)
and  a.create_time >= ‘2018-03-09 14:00:00‘;

4.Select distinct a.ann_id from 
dmdb.t_bond_ann_att_info a
where a.ann_id not in (
select id from  t_bond_ann_info
  where create_time >= ‘2018-03-09 11:10:00‘   
)
and last_update_time >= ‘2018-03-09 11:10:00‘;

5.select  * from t_bond_ann_att_info where ann_id in (‘13441‘,‘13442‘)

6.delete from t_bond_ann_att_info where ann_id in (‘13441‘,‘13442‘)

7.Select * from dmdb.t_bond_ann_info 
order by  create_time DESC
limit 800

8.select * from dmdb.t_bond_ann_att_info where ann_id=15068
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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)

 例二：

 select * from testtable
 where numeber in (select number from people group by number having count(number) > 1 )

 可以查出testtable表中number相同的记录

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 * fromvitae 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 fromvitae 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 * fromvitae 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)

(二)
比方说在A表中存在一个字段“name”，而且不同记录之间的“name”值有可能会相同，
现在就是需要查询出在该表中的各记录之间，“name”值存在重复的项；
Select Name,Count(*) From A Group By Name Having Count(*) > 1

如果还查性别也相同大则如下:
Select Name,sex,Count(*) From A Group By Name,sex Having Count(*) > 1

方法二
有两个意义上的重复记录，一是完全重复的记录，也即所有字段均重复的记录，二是部分关键字段重复的记录，
比如Name字段重复，而其他字段不一定重复或都重复可以忽略。
1、对于第一种重复，比较容易解决，使用
select distinct * from tableName
就可以得到无重复记录的结果集。

如果该表需要删除重复的记录（重复记录保留1条），可以按以下方法删除
select distinct * into #Tmp fromtableName
drop tabletableName
select * into tableName from#Tmp
drop table #Tmp

发生这种重复的原因是表设计不周产生的，增加唯一索引列即可解决。

2、这类重复问题通常要求保留重复记录中的第一条记录，操作方法如下

假设有重复的字段为Name,Address，要求得到这两个字段唯一的结果集
select identity(int,1,1) as autoID, * into #Tmp fromtableName

select min(autoID) as autoID into #Tmp2 from #Tmp group byName,autoID

select * from #Tmp where autoID in(select autoID from #tmp2)

最后一个select即得到了Name，Address不重复的结果集（但多了一个autoID字段，实际写时可以写在select子句中省去此列）

(四)
查询重复
select * from tablename where id in(
select id fromtablename 
group by id 
 having count(id) > 1 
)