转置查询输出

Question

我有一个普通的选择查询，其结果如下输出。

select cid,x1,x2,x3,x4,fy
  from temp_table;

cid     x1  x2  x3  x4  fy
----------------------------
6657    100 0   0   200 2014
6658    300 0   0   400 2015
6659    500 0   0   600 2016

我希望它重写输出以下输出。

    2014    2015    2016    
-------------------------   
x1  100     300     500     
x2  0       0       0       
x3  0       0       0       
x4  200     400     600

如何做到这一点？

Answer 1

这是仅通过子查询和聚合来完成此操作的一种方法：

select name,
       sum(case when fy = 2014 then x end) as "2014",
       sum(case when fy = 2015 then x end) as "2015",
       sum(case when fy = 2016 then x end) as "2016"
from (select fy,
             (case when n.n = 1 then 'x1'
                   when n.n = 2 then 'x2'
                   when n.n = 3 then 'x3'
                   when n.n = 4 then 'x4'
              end) as name,
             (case when n.n = 1 then x1
                   when n.n = 2 then x2
                   when n.n = 3 then x3
                   when n.n = 4 then x4
              end) as x
      from temp_table cross join
            (select 1 as n from dual union all
             select 2 from dual union all
             select 3 from dual union all
             select 4 from dual
            ) n
     ) t
group by name;

您也可以使用pivot，但这是Oracle SQL的最新功能，因此我倾向于使用此方法。