SQL:删除表中重复的记录

SQL sql

2015-07-29 0 614


--创建测试表
if object_id(\'test\') is not null 
  drop table test

create table test
(
 id int identity(1,1) primary key,
 name varchar(50)
)

--插入几条测试数据
insert into test select \'a\' union all
select \'a\' union all
select \'a\' union all
select \'a\' union all
select \'a\' union all
select \'a\' union all
select \'b\' union all
select \'b\' union all 
select \'b\' union all 
select \'b\' union all 
select \'b\' union all 
select \'b\' union all
select \'b\' union all
select \'c\' union all 
select \'c\' union all 
select \'c\' union all 
select \'d\' union all 
select \'d\'

--查看当前记录
select * from test

if object_id(\'#\') is not null 
  drop table #
--注意(是单个字段的不同还是多个字段,这里是name)
select distinct (name) into # from test
--查看新表中的数据
select * from #
--清空旧表
truncate table test
--将新表中的数据插入到旧表
insert test select * from #
--删除新表
drop table #
--查看结果
select * from test

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 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)

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