mysql删除子查询中的记录语句

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mysql删除子查询中的记录语句

来源: 作者: 时间:2016-02-03 08:56 【

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
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 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

 

 
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