如何检查每个组中是否存在值（分组后） [英] How to check if value exists in each group (after group by)

问题描述

假设我有一个订阅表：

uid  | subscription_type 
------------------------  
Alex | type1
Alex | type2
Alex | type3
Alex | type4
Ben  | type2
Ben  | type3
Ben  | type4

并且只想选择拥有2个以上订阅但从未订阅过1类的用户

And want to select only the users that have more than 2 subscriptions but never subscribed with type 1

预期结果仅选择 Ben。

The expected result is selecting "Ben" only.

我很容易找到拥有2个以上用户的用户订阅使用：

I easy can found the users that have more than 2 subscribes using:

SELECT uid
FROM subscribes
GROUP BY uid
HAVING COUNT(*) > 2

但是如何检查组中是否不存在某些值？

But how to check if in a group some value never exists?

感谢您的帮助！

推荐答案

尝试以下查询：

SELECT uid 
FROM subscribes 
GROUP BY uid 
HAVING COUNT(*) > 2
   AND max( CASE "subscription_type"  WHEN 'type1' THEN 1 ELSE 0 END ) = 0

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