mysql - 统计付费用户的不同数量

Question

这是我的输入表(选项卡)，其中包含用户 ID 和“已验证购买”。 (用户可以尝试购买，但可能决定不购买。因此已验证购买)

UserID   Verified_Purchase
 1001          T
 1001          T 
 1001          F   
 1002          T 
 1002          T
 1003          F
 1004          T
 1004          F


My expected output is to find out the no of unique buyers / non buyers. 
No of Buyers :  3  (1001,1002,1004)
No of Non Buyers : 1 (only 1003)

我尝试过:

select distinct UserID from tab
WHERE Verified_Purchase = 'T'

select distinct UserID from tab
WHERE Verified_Purchase = 'F'

但是这些并没有给出正确的答案，因为很少有用户被重复计算。

请告诉我如何继续进行同样的操作。

Answer 1

首先按userId汇总，然后聚合:

select is_verified, count(*) as num_users
from (select UserId, max( Verified_Purchase = 'T' ) as is_verified
      from tab t
      group by UserId
     ) t
group by is_verified;