比如现在有一人员表 （表名：peosons）
若想将姓名、身份证号、住址这三个字段完全相同的记录查询出来
selectp1.*frompersonsp1,personsp2wherep1.id<>p2.idandp1.cardid=p2.cardidandp1.pname=p2.pnameandp1.address=p2.address
可以实现上述效果．
几个删除重复记录的sql语句
1.用rowid方法
2.用group by方法
3.用distinct方法
1。用rowid方法
据据oracle带的rowid属性，进行判断，是否存在重复,语句如下：
查数据:
select * from table1 a where rowid !=(selectmax(rowid)
from table1 b where a.name1=b.name1 and a.name2=)
删数据：
deletefrom table1 a where rowid !=(selectmax(rowid)
from table1 b where a.name1=b.name1 and a.name2=)
2.group by方法
查数据:
select count(num), max(name) from student --列出重复的记录数，并列出他的name属性
group by num
having count(num) >1 --按num分组后出表中num列重复，即出现次数大于
一次
删数据：
delete from student
group by num
having count(num) >1
这样的话就把所有重复的都删除了。
3.用distinct方法 -对于小的表比较有用
create table table_new asselect distinct *from table1 minux
truncate table table1;
insert into table1 select * from table_new;
查询及删除重复记录的方法大全
1、查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
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 peopleidhaving count(peopleid) > 1)
and rowid not in (select min(rowid) from people group by peopleid having count(peopleid )>1)
3、查表中多余的重复记录（多个字段）
select * from vitae a
where
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) (a.peopleid,a.seq) in (select peopleid,seq from vitae group by peopleid,seq having count(*) > 1) peopleid in (select peopleid from people group by peopleid having count(peopleid) > 1)
5、查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)
(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
(三)
方法一 declare @max integer,@id integer declare cur_rows cursor local for select 主字段,count(*) from 表名 group by 主字段 having count(*) >； 1 open cur_rows fetch cur_rows into @id,@max while @@fetch_status=0 begin select @max = @max -1 set rowcount @max delete from 表名 where 主字段 = @id fetch cur_rows into @id,@max end close cur_rows set rowcount 0
方法二 ＂重复记录＂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。
distinct查询 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 from tablename drop table tablename 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 from tablename select min(autoid) as autoid into #tmp2 from #tmp group by name,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 from tablename group by id having count(id) > 1 )篇二：查询和删除表中重复数据sql语句
查询和删除表中重复数据sql语句
1、查询表中重复数据。
select * from people
where peopleid in
(selectpeopleidfrompeoplegroupbypeopleidhaving
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 peopleidin (selectpeopleidfrom
peoplegroupbypeopleid havingcount(peopleid) > 1) and rowid not in (select min(rowid) frompeoplegroup by
peopleidhaving count(peopleid )>1)
3、查表中多余的重复记录（多个字段）
elect * from vitae a
where (a.peopleid,a.seq) in(select peopleid,seq from vitae group by
peopleid,seqhaving count(*) > 1)
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