Order by statement - 按多列排序

Question

我有 table 这样的：

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

所以，我按语句“按 B 排序”进行排序，结果如下：

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

但是，我该怎么做才能得到这个排序：

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

如果 C 列不为空，我应该将此行放在 A = C 的行后

谢谢！

所以，在这种情况下：

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

我有那个输出（C 777 在 A 111 之后，因为 B 值相同 = 4）：

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

但我想得到这个：

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

Answer 1

这样做：

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

就是这样：

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

Answer 2

可能对你有帮助:

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

输出

选择了 7 行

或者如您稍后所说，您可以同时拥有非空 A 和 C 列，您可以这样做：

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

输出

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

 8 rows selected

Order by statement - 按多列排序

Order by statement - ordering by multiple columns

sql

oracle

sql-order-by