MySQL查询表内重复记录

欢迎进入Linux社区论坛，与200万技术人员互动交流 >>进入 MySQL查询表内重复记录 (一) 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 havi

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　　MySQL查询表内重复记录

　　(一)

　　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，只留有一个记录

　　delete from people

　　where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1)

　　and min(id) not in (select id 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

　　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