select * from o  
order by 
 case 
  when id = 4 then 1 
  when id = 5 then 2 
  when id = 1 then 3 
  when id = 2 then 4
  when id = 3 then 5 
 end

------解决方案--------------------
还有一种方法
SQL code
select * from o  
order by 
  charindex(','+ltrim(id)+',',',4,5,1,2,3,')

------解决方案--------------------
SQL code

--正确
select * from o  
order by 
 case 
  when id = 4 then 1 
  when id = 5 then 2 
  when id = 1 then 3 
  when id = 2 then 4
  when id = 3 then 5 
 end 

--错误
select * from o  
order by case when id = 4 then 1 end,--end当id<>4时，语句就停止了
 case when id = 5 then 2 end,
 case when id = 1 then 3 end,
 case when id = 2 then 4 end,
 case when id = 3 then 5 end