Oracle SQL 转置数据

Question

我有一个要求，我的数据来自这样的表

country  total_population  number_of_cities  number_of_airports
US        1,000,000,000          500                25
UK        2,000,000,000          400                20

这是动态数据。我需要显示的结果是这样的

                         US              UK
total_population    1,000,000,000       2,000,000,000
number_of_cities       500               400
number_of_airports      25                20

我怎样才能做到这一点？非常感谢任何帮助或指点。

Answer 1

您可以组合使用 MAX、CASE 和 UNION ALL。

 SELECT 'total_population' metric,
       MAX(CASE
             WHEN country = 'US' THEN total_population
           END)           US,
       MAX(CASE
             WHEN country = 'UK' THEN total_population
           END)           UK
FROM   yourtable
UNION ALL
SELECT 'number_of_cities' metric,
       MAX(CASE
             WHEN country = 'US' THEN number_of_cities
           END)           US,
       MAX(CASE
             WHEN country = 'UK' THEN number_of_cities
           END)           UK
FROM   yourtable
UNION ALL
SELECT 'number_of_airports' metric,
       MAX(CASE
             WHEN country = 'US' THEN number_of_airports
           END)             US,
       MAX(CASE
             WHEN country = 'UK' THEN number_of_airports
           END)             UK
FROM   yourtable;

DEMO

Answer 2

这是需求的解决方案。它基本上需要交换行和列。这可以通过先取消旋转然后再旋转回来来实现。这是查询

select *
from (
    select 
        country,
          total_population, number_of_cities, number_of_airports
      FROM yourtable 
      ) unpivot ( val for stats in (total_population, number_of_cities, number_of_airports))
    pivot (sum(val) for country in ('US', 'UK'));

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