mysql删除子查询中的记录语句_MySQL

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mysql删除子查询中的记录语句

 

Sql代码  delete from t_5star where  locationid in  (        select e.locationid  from  (              select a.*  from t_5star as a ,              t_als_data as b where a.term =  b.term ) e   )  

 

关键是子查询中的语句要放到单一e的表中

 

查询及删除重复记录的方法

(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

Sql代码  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 peoplewhere 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 awhere (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 awhere (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 awhere (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

 

 

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