ORDER BY語句 - 排序由多個列

Question

我的表是這樣的：

A  B  C 
----------------------- 
111  3 
       777 
333  1 
555  2 
       333 
777  4 
888  5 

所以，我必須聲明令「經B順序」和我有結果是這樣的：

A  B  C 
---------------------- 
333  1 
555  2 
111  3 
777  4 
888  5 
       777 
       333 

但是，我能做些什麼來得到這個排序：

A  B  C 
----------------------- 
333  1 
       333 
555  2 
111  3 
777  4 
       777 
888  5 

如果列C時不爲空，我應該排wher後把此行e A = C

謝謝！

所以，在這種情況下：

with a(a,b,c) as (select 111,4, null from dual union all 
        select null,null,777 from dual union all 
        select 333,1,null from dual union all 
        select 555,2, null from dual union all 
        select null,null, 333 from dual union all 
        select 777, 4, null from dual union all 

        select 444,null, 333 from dual union all 

        select 888, 5, null from dual union all 
        select null,null,777 from dual) 

select a.* 
    from a 
order by last_value(b ignore nulls) 
     over (partition by CASE when b is null then c else a end order by b), b nulls last 

我有輸出（C 777是A 111後，因爲B值是相同= 4）：

A B  C 
--------------------   
333  1 
444   333 
      333 
555  2 
777  4 
111  4 
      777 
      777 
888  5 

但我要得到這樣的：

A B  C 
    -------------------- 
    333  1 
    444   333 
       333 
    555  2 
    777  4 
       777 
       777 
    111  4 
    888  5 

Answer 1

可能是這個幫助你：

with a(a,b,c) as (select 111,3, null from dual union all 
        select null,null,777 from dual union all 
        select 333,1,null from dual union all 
        select 555,2, null from dual union all 
        select null,null, 333 from dual union all 
        select 777, 4, null from dual union all 
        select 888, 5, null from dual) 

select a.* 
    from a 
order by last_value(b ignore nulls) over (partition by nvl(a,c) order by b), b nulls last 

輸出

333 1 
     333 
555 2 
111 3 
777 4 
     777 
888 5 

7行中選擇

或像你說的以後，你可以擁有兩個不空A和C柱，你可以這樣做：

with a(a,b,c) as (select 111,3, null from dual union all 
        select null,null,777 from dual union all 
        select 333,1,null from dual union all 
        select 555,2, null from dual union all 
        select null,null, 333 from dual union all 
        select 777, 4, null from dual union all 

        select 444,null, 333 from dual union all 

        select 888, 5, null from dual) 

select a.* 
    from a 
order by last_value(b ignore nulls) 
     over (partition by CASE when b is null then c else a end order by b), b nulls last 

輸出

  A   B   C 
     333   1    
          333 
     444     333 
     555   2    
     111   3    
     777   4    
          777 
     888   5    

8 rows selected 

Answer 2

做這樣的：

select case when C in not null then C else A end as A,B,C from table 

它一樣是這樣的：

Declare @c nchar(50) 
Declare @a nchar(50) 
set @c = 'record' 
set @a = 'sample' 
select case when @c is not null then @c else @a end as A,@c as C