如何在我的MySQL使用GROUP_CONCAT

Question

我有這個疑問：

select IF(user_name IS NULL or user_name= '', distinct_id, user_name) 
     as user_info, event, count(event) as event_count 
    from mixpanel 
    where 
     (mixpanel.event = 'app_open' or 
     mixpanel.event = 'post_created' or 
     mixpanel.event = 'create_comment' or 
     mixpanel.event = 'class_opened' or 
     mixpanel.event = 'post_read') 
    AND 
     class_id = 'AKSJSDKSD' 

    group by event, user_name, distinct_id 
    order by user_name desc 

，它給了我下面的結果：

+-----------+------------+--------+ 
| user_info | event | event_count | 
+-----------+------------+--------+ 
| Ben Cho | up | 12   | 
| Lee Mar | up | 21   | 
| Lee Mar | side | 12   | 
| Lee Mar | down | 16   | 
| Al Gov | up | 14   | 
| Al Gov | down | 13   | 
| Al Gov | side | 13   | 
+-----------+------------+--------+ 

我需要的是聚集像這樣每個用戶數據：

+-----------+------------+--------+ 
| user_info | up | down | side 
+-----------+------------+--------+ 
| Ben Cho | 12 | 0 | 0  | 
| Lee Mar | 21 | 16 | 12 | 
| Al Gov | 14 | 13 | 13 | 
+-----------+------------+--------+ 

我該如何在mySql上實現這個功能？

謝謝！

Answer 1

從我可以告訴你，你只是想條件聚合。不需要group_concat()：

select (case when user_name IS NULL or user_name = '' then distinct_id else user_name 
     end) as user_info, 
     sum(mp.event = ('app_open')) as num_app_open, 
     sum(mp.event = ('post_created')) as num_post_created, 
     sum(mp.event = ('create_comment')) as num_create_comment 
from mixpanel mp 
where mp.event in ('app_open', 'post_created', 'create_comment') and 
     class_id = '-KtmM9EACwDTR98a_yU9' 
group by user_info 
order by user_info desc;