mysql - Mysql Count 几个字段

Question

我有一张桌子

id|user_id|开始|停止
 1| 1| 1| 1
 2| 2| 1| 1
 3| 2| 1| 0
 4| 3| 0| 0

我想得到下一个结果

user_id|总计|开始|停止
      1| 1| 1| 1
      2| 2| 2| 1
      3| 1| 0| 0

所以我想计数 3 并按 user_id ang get 分组。是否可以使用联接而不使用派生表来准备查询？

Answer 1

SELECT user_id, 
       Sum (start) AS start, 
       Sum (stop)  AS stop, 
       Count(*)    AS total 
FROM   tablename 
GROUP  BY user_id 

Answer 2

SELECT   user_id, COUNT(*) total, SUM(start=1) start, SUM(stop=1) stop
FROM     my_table
GROUP BY user_id

Answer 3

总行数为 1 instart和 1 instop 两次。

SELECT user_id, 
   count(case start WHEN 1 then 1 else null end) AS start, 
   count(case stop WHEN 1 then 1 else null end)  AS stop, 
   count (*) AS total 
FROM   tablename 
GROUP  BY user_id