Oracle数据库中关于"null"排序的问题

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问题：在处理一般的数据记录中，对于数字类型的字段，在oracle的排序中，默认把null值做为大于任何数字的类型，当然对于varchar2类型的字段，默认也是该处理方式，但是客户要求排序的过程中，需要把null的字段默认排在前边(从小-->大)。一般的order by xxxx，无法解决。

问题解决：

示例如下：

select * from 

(select a.*,rownum as my_sys_rownum from ( 

select deptid,nvl(BDZNAME," "),nvl(VOLLEVEL,"0"),ZBRL,nvl　(ZBTS, "0"), 

nvl(FZR,"0"),nvl(DEPTIDDES," "),nvl(TEL," "),nvl(RUNSTATEDES," "), 

nvl(ADDRESS," "),BDZID from V_BDZ where rownum<2000 

and ZBRL is null 

) a 
union 

select b.*,rownum+(select count(*) from ( 

select deptid,nvl(BDZNAME," "),nvl(VOLLEVEL,"0"),ZBRL,nvl(ZBTS, "0"), 

nvl(FZR,"0"),nvl(DEPTIDDES," "),nvl(TEL," "),nvl　(RUNSTATEDES," "), 

nvl(ADDRESS," "),BDZID from V_BDZ where rownum<2000 

and ZBRL is null 

)) as my_sys_rownum from ( 

select deptid,nvl(BDZNAME," "),nvl(VOLLEVEL,"0"),ZBRL, 

nvl(ZBTS, "0"),nvl(FZR,"0"), 

nvl(DEPTIDDES," "),nvl(TEL," "),nvl(RUNSTATEDES," "), 

nvl(ADDRESS," "),BDZID from V_BDZ where rownum<2000 

and ZBRL is not null order by ZBRL 

) b 

) 

order by my_sys_rownum desc 数据挖掘论坛

（责任编辑；卢兆林）

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