请教Oracel Where case 查询方式

Question

本帖最后由 dongguangxiang 于 2011-04-29 10:47:38 编辑

Answer 1

应该是说  即便通过了  也达不到你的目的吧。你试试下面这样是否可行？select *
from (                        
      select 1, e1.*
      from TBWKPQUICKMENUCUSTREL  e1
      where e1.IUSERID = 2805       union       select 2, e2.* 
      from TBWKPQUICKMENUCUSTREL  e2
      where e2.IROLEID = 0
      ) t
where rownum < 2

Answer 2

select a.*,
   (case
    when (select count(*) from TBWKPQUICKMENUCUSTREL where IUSERID  = 2805) > 0 then
          (select  1
             from TBWKPQUICKMENUCUSTREL  B
            where a.IUSERID  = b.IUSERID 
              and B.IUSERID   = 2805)
         else
          (select 1
             from TBWKPQUICKMENUCUSTREL   B
            where A.IUSERID  = b.IUSERID  
              and b.IUSERID  = 0)
       end) countnumber
  from TBWKPQUICKMENUCUSTREL   a
  where rownum<=1

Answer 3

         select *
         from TBWKPQUICKMENUCUSTREL where decode(IUSERID,2805,1,0)+decode(IROLEID,0,1,0)=1