SQL重复记录查询 查询多个字段、多表查询、删除

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来判断

select * from people where peopleId in (select peopleId from people group by peopleId having count 

例二:

select * from testtable where numeber in (select number from people group by number having count 

可以查出testtable表中number相同的记录

2、删除表中多余的重复记录,重复记录是根据单个字段来判断,只留有rowid最小的记录

delete from people where peopleId in (select peopleId from people group by peopleId having count and rowid not in  from people group by peopleId having count 

金沙官网线上,3、查找表中多余的重复记录

select * from vitae a where  in (select peopleId,seq from vitae group by peopleId,seq having count 

4、删除表中多余的重复记录,只留有rowid最小的记录

delete from vitae a where  in (select peopleId,seq from vitae group by peopleId,seq having count and rowid not in  from vitae group by peopleId,seq having count 

5、查找表中多余的重复记录,不包含rowid最小的记录

select * from vitae a where  in (select peopleId,seq from vitae group by peopleId,seq having count and rowid not in  from vitae group by peopleId,seq having count 

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 

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 

方法二

有两个意义上的重复记录,一是完全重复的记录,也即所有字段均重复的记录,二是部分关键字段重复的记录,比如Name字段重复,而其他字段不一定重复或都重复可以忽略。

1、对于第一种重复,比较容易解决,使用

select distinct * from tableName 

就可以得到无重复记录的结果集。

如果该表需要删除重复的记录,可以按以下方法删除

select distinct * into #Tmp from tableName drop table tableName select * into tableName from #Tmp drop table #Tmp 

发生这种重复的原因是表设计不周产生的,增加唯一索引列即可解决。

2、这类重复问题通常要求保留重复记录中的第一条记录,操作方法如下

假设有重复的字段为Name,Address,要求得到这两个字段唯一的结果集

select identity as autoID, * into #Tmp from tableName select min as autoID into #Tmp2 from #Tmp group by Name,autoID select * from #Tmp where autoID in(select autoID from #tmp2) 

最后一个select即得到了Name,Address不重复的结果集(但多了一个autoID字段,实际写时可以写在select子句中省去此列)

select * from tablename where id in ( select id from tablename group by id having count 

以上就是小编为大家带来的SQL重复记录查询 查询多个字段、多表查询、删除重复记录的方法的全部内容了,希望对大家有所帮助,多多支持脚本之家~

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