oracle去掉重复记录语句

oracle去掉重复记录语句

  比如现在有一人员表 （表名：peosons） 若想将姓名、身份证号、住址这三个字段完全相同的记录查询出来 select p1.*   from persons  p1,persons  p2   where p1.id<>p2.id   and  p1.cardid = p2.cardid and p1.pname = p2.pname and p1.address = p2.address   可以实现上述效果．    www.2cto.com   几个删除重复记录的SQL语句   1.用rowid方法   2.用group by方法   3.用distinct方法   1。用rowid方法   据据oracle带的rowid属性，进行判断，是否存在重复,语句如下：   查数据:        select * from table1 a where rowid !=(select max(rowid)      from table1 b where a.name1=b.name1 and a.name2=b.name2......)   删数据：       delete  from table1 a where rowid !=(select max(rowid)     from table1 b where a.name1=b.name1 and a.name2=b.name2......)   2.group by方法   查数据:   　　select count(num), max(name) from student --列出重复的记录数，并列出他的name属性 　　group by num 　　having count(num) >1 --按num分组后找出表中num列重复，即出现次数大于一次   删数据：   　　delete from student 　　group by num 　　having count(num) >1 　　这样的话就把所有重复的都删除了。   3.用distinct方法 -对于小的表比较有用   create table table_new as   select distinct *   from table1 minux truncate table table1; insert into table1 select * from table_new;   查询及删除重复记录的方法大全   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   (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   方法二 ＂重复记录＂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（重复记录保留1条），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(int,1,1) as autoID, * into #Tmp from tableName select min(autoID) 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）   (四) 查询重复 select * from tablename where id in ( select id from tablename group by id having count(id) > 1 ) 例子 delete from w_m_mjout where ksid in (select ksid from tableName group by ksid HAVING COUNT(ksid)>1) and rowid not in (select min(ROWID) from tableName group by ksid HAVING COUNT(ksid)>1)  

oracle去掉重复记录语句

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