oracle删除重复记录

klona1988 贡献于2012-03-23

作者 雨林木风  创建于2012-03-22 08:57:00   修改者微软用户  修改于2012-03-22 08:57:00字数3076

文档摘要:oracle删除重复记录
关键词:

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. 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 cmcc where cmcc_id in (select cmcc_id from people group by cmcc_id having count(cmcc_id) > 1) and rowid not in (select min(rowid) from cmcc group by cmcc_id having count(cmcc_id )>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)

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