当前位置:Gxlcms > mysql > MySQL查询表内重复记录

MySQL查询表内重复记录

时间:2021-07-01 10:21:17 帮助过:4人阅读

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

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 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

人气教程排行