SQL重复记录查询
SQL重复记录查询
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 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)
(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
s
相关文档：
SQL中on条件与where条件的区别
数据库在通过连接两张或多张表来返回记录时，都会生成一张中间的临时表，然后再将这张临时表返回给用户。
在使用left jion时，on和where条件的区别如下：
1、 on条件是在生成临时表时使用的条� ......
Kagula
2009-11-17
关键词
Java My SQL
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要求环境：
J2SE1.5 + Eclipse3.4.2
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select name,sum(case subject when '数学' then source else 0 end) as '数学',
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