Question

如何为另一个表中的所有组重复表中的所有行？

Answer 1

从指定日期做一个简单的SELECT COUNT吗？

SELECT month_start, next_month_start, sum(cnt) as users, dept FROM
(SELECT CASE WHEN created_at<=next_month_start AND created_at>=month_start THEN 1 ELSE 0 END as cnt,
users.*, month_start, next_month_start FROM users
CROSS JOIN dates) as S1
GROUP BY dept, month_start, next_month_start ORDER BY dept DESC

Answer 2

 SELECT D.id dates_id,D.month_start dates_start,D.next_month_start dates_next_month_start,count(U.id) user_created,U.dept 

 FROM dates D 
 LEFT JOIN users U ON concat(year(U.created_at) ,"-",month(U.created_at)) = concat(year(D.month_start) ,"-",month(D.month_start)) 

 GROUP BY concat(year(D.month_start) ,"-",month(D.month_start)) ,concat(year(D.next_month_start) ,"-",month(D.next_month_start)) ;

以下是输出

id  month_start                 next_month_start             user_created   dept
7   February, 01 2016 00:00:00  March, 01 2016 00:00:00       0             (null)
6   March, 01 2016 00:00:00     April, 01 2016 00:00:00       2             sales
5   April, 01 2016 00:00:00     May, 01 2016 00:00:00         3             sales
4   May, 01 2016 00:00:00       June, 01 2016 00:00:00        0             (null)
3   June, 01 2016 00:00:00      July, 01 2016 00:00:00        2              hr
2   July, 01 2016 00:00:00      August, 01 2016 00:00:00      0             (null)
1   August, 01 2016 00:00:00    September, 01 2016 00:00:00   0             (null)

Answer 3

你需要这样的东西吗？

SELECT sum(cnt), month_start, next_month_start, dept
 FROM
 (
  SELECT
    CASE WHEN created_at<=next_month_start AND created_at>=month_start THEN 1 ELSE 0 END cnt,
    users.*, month_start, next_month_start
   FROM users
   CROSS JOIN dates
 ) sbt
 GROUP BY month_start, next_month_start, dept

Answer 4

试试这个，

SELECT d.*, dp.dept, u.users_created
FROM dbo.dates d
CROSS APPLY ( SELECT DISTINCT dept FROM dbo.users ) as dp
OUTER APPLY ( SELECT COUNT(*) users_created 
              FROM dbo.users u 
              WHERE u.dept = dp.dept
              AND u.created_at >= d.month_start 
              AND u.created_at < d.next_month_start
            ) as u

如何为另一个表中的所有组重复表中的所有行？

4 个答案: