case when的疑点

case when的疑问
数据库里有1,2,3,4,5共5条记录,要用一条sql语句让其排序,使它排列成4,5,1,2,3
第一种：
select * from o 
 order by case id when 4 then 1
  when 5 then 2
  when 1 then 3
  when 2 then 4
  when 3 then 5 end
第二种：
select * from o 
order by case when id = 4 then 1 end,
 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 
第一种方式可以实现功能,但第二种方式却不能,为什么？这两种方式有什么区别？？？

[解决办法]
第二种

SQL code

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
[解决办法]
还有一种方法
SQL code
select * from o  order by   charindex(','+ltrim(id)+',',',4,5,1,2,3,')
[解决办法]
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