删除重复记录(sql) case when

select 姓名,工龄,
(case when (工龄>= '35') then '90%'
when (工龄>='30' and 工龄<'35') then '85%'
when (工龄>='20' and 工龄<'30') then '80%'
when (工龄>='10' and 工龄<'20') then '70%'
else  0 end) as '计算比例'
from 表

case when sql
select (case when t2.channel_state=1 then '在线' when t2.channel_state=0 then '在线1' end ),t2.* from X_PAY_CHANNEL_INFO t2

1>CREATE TABLE X_TEMP_ATTRVAL AS
    (select to_char(attr_id) as attr_id, value, count(*)as count, to_char(min(attrval_id)) as attrval_id
          from attrvaldesc t2
         where t2.language_id = -7
         group by attr_id, value
        having count(*) > 1)   

2>delete from x_catentryattr_store xca
where xca.attrval_id in (select atv1.attrval_id
                             from attrvaldesc atv1, (X_TEMP_ATTRVAL) b1
                            where atv1.attrval_id != b1.attrval_id
                              and atv1.attr_id = b1.attr_id
                              and nvl(atv1.value,0) = nvl(b1.value,0)
                              and atv1.language_id = -7)
                             
3>
delete from attrval atv2
where atv2.attrval_id in (select atv.attrval_id
                             from attrvaldesc atv, (X_TEMP_ATTRVAL) b
                            where atv.attrval_id != b.attrval_id
                              and atv.attr_id = b.attr_id
                              and nvl(atv.value,0) = nvl(b.value,0)
                              and atv.language_id = -7)                                     

4>
CREATE TABLE X_TEMP_ATTR AS
    （select  a.store_id,a.catentry_id, to_char(a.attr_id) as attr_id, min(to_char(a.attrval_id)) as attrval_id,
count(*) as count from x_catentryattr_store a ,attrval b,attr c where a.attrval_id=b.attrval_id and
  b.attr_id=c.attr_id and a.attr_id=c.attr_id and c.attrusage is null and a.usage=2
group by a.catentry_id, a.attr_id, a.store_id
having count（* ） > 1）
          
5>
delete from attrval av where av.attrval_id in (select xc.attrval_id from x_catentryattr_store xc
where xc.store_id||'_'||xc.catentry_id||'_'||xc.attr_id||'_'||
xc.attrval_id in
       (select a.store_id||'_'||
               a.catentry_id||'_'||
               to_char(a.attr_id)||'_'||
               to_char(a.attrval_id)
          from x_catentryattr_store a, X_TEMP_ATTR b
         where a.store_id = b.store_id
           and a.catentry_id = b.catentry_id
           and a.attr_id = b.attr_id
           and a.attrval_id != b.attrval_id))
           
6> delete from x_catentryattr_store xc
where xc.store_id||'_'||xc.catentry_id||'_'||xc.attr_id||'_'||
xc.attrval_id in
       (select a.store_id||'_'||
               a.catentry_id||'_'||
               to_char(a.attr_id)||'_'||
               to_char(a.attrval_id)
          from x_catentryattr_store a, X_TEMP_ATTR b
         where a.store_id = b.store_id
           and a.catentry_id = b.catentry_id
           and a.attr_id = b.attr_id
           and a.attrval_id != b.attrval_id)


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.idp2.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 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