Question

oracle order by在同一列可以某些值升序 某些值降序吗

Answer 1

这个是不行的，但是你可以用case when 语句把你要排序的值转换下，例如：
--t表里的值是'a','b','c','d'，我要它按照'd','b','c','a'排序
select t.*,
case
when t.id = 'd' then
1
when t.id = 'b' then
2
when t.id = 'c' then
3
else
4
end rn
from (select 'a' as id
from dual
union all
select 'b' as id
from dual
union all
select 'c' as id
from dual
union all
select 'd' as id from dual) t
order by case
when t.id = 'd' then
1
when t.id = 'b' then
2
when t.id = 'c' then
3
else
4
end

Answer 2

当然是不行的，要么ascd，要么desc.

Answer 3

肯定不可以的