当value_2，value_3等于某个值时计算distinct value_1答案

【问题标题】：Calculate distinct value_1 when value_2, value_3 is equal to certain value当value_2，value_3等于某个值时计算distinct value_1
【发布时间】：2020-06-03 13:22:32
【问题描述】：

输出表如下所示：

table : people
+-------+-----------+-----------+
|   id  |  label    |   action  |
+-------+-----------+-----------+
|   1   |  aaaaa    |       B   |
|   1   |  aaaaa    |       B   |
|   1   |  aaaaa    |       A   |
|   2   |  aaaaa    |       B   |
|   2   |  aaaaa    |       B   |
+-------+-----------+-----------+

我想做的是以这种方式计算唯一 ID：

table : people
+-------+-----------+-------------+-------------+
|   id  |  label    |   action_A  |   action_B  |
+-------+-----------+-------------+-------------+
|   1   |  aaaaa    |       1     |       1     |
|   2   |  aaaaa    |       0     |       1     |
+-------+-----------+-------------+-------------+

【问题讨论】：

即使出现两次，您确定只希望结果中的 action_B 计数一次吗？
是的@ManfredMoser :)

标签： sql count case amazon-athena

【解决方案1】：

只使用条件聚合：

SELECT id, label, 
   coalesce(max(1) filter (WHERE action = 'A'), 0) action_a,
   coalesce(max(1) filter (WHERE action = 'B'), 0) action_b
FROM ...
GROUP BY 1, 2

【讨论】：

【解决方案2】：

只使用条件聚合：

select id, label,
       sum(case when label = 'A' then 1 else 0 end) as a,
       sum(case when label = 'B' then 1 else 0 end) as b
from t
group by id, label;

【讨论】：

【解决方案3】：

你可以做条件聚合：

select id, label, 
       count(distinct case when action = 'A' then action end) as action_a,
       count(distinct case when action = 'B' then action end) as action_b
from t
group by id, label;

或者你可以使用max()：

select id, label, 
       max(case when action = 'A' then 1 else 0 end) as action_a,
       max(case when action = 'B' then 1 else 0 end) as action_b
from t
group by id, label;

【讨论】：