使用 Teradata 按组计算百分比

Question

我正在尝试创建一个表格，显示取决于指标的每个状态的计数百分比。

这是我用来创建新表的数据集示例。

+-------------+-------+-------+
|  Indicator  | State | Count | 
+-------------+-------+-------+
| Registered  | CA    |    25 |
| Registered  | FL    |    12 |
| Total       | CA    |    50 |
| Total       | FL    |    36 |
+-------------+-------+-------+

我正在尝试创建一个新表，其中每个对应行都有一个百分比，如下所示：

+-------------+-------+-------+------------+
|  Indicator  | State | Count | Percentage |
+-------------+-------+-------+------------+
| Registered  | CA    |    25 |         50 |
| Registered  | FL    |    12 |       33.3 |
| Total       | CA    |    50 |          . |
| Total       | FL    |    36 |          . |
+-------------+-------+-------+------------+

到目前为止，我已尝试执行以下查询：

select indicator, state, count
, case when (select count from table where indicator='Registered') * 100 / (select count from table where indicator='Total')
when indicator = 'Total' then . end as Percentage

from table;

这不起作用，因为我收到一个错误：“子查询评估了不止一行。”我猜是因为我没有考虑 case when 语句中的状态，但我不确定我会如何去做。

最好的方法是什么？

Answer 1

只需将表与自身连接起来。

select a.indicator, a.state, a.count
     , case when (indicator='Total') then null
            else 100 * a.count/b.count 
       end as Percentage
from table a
inner join (select state,count from table where indicator='Total') b 
  on a.state = b.state
;

Answer 2

你可以使用窗口函数：

select t.*,
       (case when indicator <> 'Total'
             then count * 100.0 / sum(case when indicator = 'Total' then indicator end) over (partition by state)
        end) as percentage
from t;