Oracle数据库中关于“null”排序的问题


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

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