Question

假设一个简单的表包含两个用户的状态事件。 status_id为1使它们“活动”，其他任何东西都使它们处于非活动状态。我需要找出所有在一年之内> 处于非活动状态的用户，例如2015-05-01（不包括该日期）。

CREATE TABLE user_status(
      user_id INT,
      status_id INT,
      date_assigned VARCHAR(10) );

 INSERT INTO user_status( user_id, status_id, date_assigned)
 VALUES
 (1234, 1, '2015-01-01'), -- 1234 becomes active (status id = 1)
 (1234, 2, '2015-07-01'), -- 1234 de-activated for reason 2

 (5678, 1, '2015-02-01'), -- 5678 becomes active (status id = 1)
 (5678, 3, '2015-04-01'), -- 5678 de-activated for reason 3
 (5678, 5, '2015-06-01'); -- 5678 de-activated for reason 5

使用查询

SELECT t1.*
FROM user_status t1
WHERE t1.date_assigned = (SELECT MIN(t2.date_assigned)       -- the first occurrence
                          FROM  user_status t2
                          WHERE t2.user_id =  t1.user_id     -- for this user
                          AND t2.status_id <> 1              -- where status not active
                          AND t2.date_assigned BETWEEN       -- within 1 yr of given date
                               '2015-05-01' + INTERVAL 1 DAY -- (not including that date)
                          AND 
                               '2015-05-01' + INTERVAL 1 YEAR 
                          )

我可以得到结果

user_id   status_id   date_assigned
 1234       2          2015-07-01
 5678       5          2015-06-01

这是正确的，但用户5678不应该在那里，因为尽管他们在日期范围内有非活动事件，但他们在所需日期范围开始之前已经处于非活动状态，因此不活动在这个范围内。

我需要在我的查询中添加一点“只显示那些有非活动事件的用户和，其中该用户的上一个status_id为1，即他们在非活动事件发生的时间。

任何人都可以帮我解决语法问题吗？见SQL fiddle

Answer 1

您可以在查询中添加NOT EXISTS：

SELECT t1.*
FROM user_status t1
WHERE t1.date_assigned = (SELECT MIN(t2.date_assigned)       -- the first occurance
                          FROM  user_status t2
                          WHERE t2.user_id =  t1.user_id     -- for this user
                          AND t2.status_id <> 1              -- where status not active
                          AND t2.date_assigned BETWEEN       -- within 1 yr of given date
                               '2015-05-01' + INTERVAL 1 DAY -- (not including that date)
                          AND 
                               '2015-05-01' + INTERVAL 1 YEAR 
                          )
      AND NOT EXISTS (SELECT 1                         -- such a record should not exist
                      FROM user_status t3
                      WHERE t3.user_id =  t1.user_id   -- for this user
                             AND t3.status_id <> 1     -- where status is not active
                             AND t3.date_assigned <    -- before the examined period
                               '2015-05-01' + INTERVAL 1 DAY )

Demo here

修改

您可以使用以下查询，该查询也考虑具有多个激活日期的情况：

SELECT * FROM user_status WHERE (user_id, date_assigned) IN ( -- get last de-activation date SELECT t1.user_id, MAX(t1.date_assigned) FROM user_status AS t1 JOIN ( -- get last activation date SELECT user_id, MAX(date_assigned) AS activation_date FROM user_status WHERE status_id = 1 GROUP BY user_id ) AS t2 ON t1.user_id = t2.user_id AND t1.date_assigned > t2.activation_date GROUP BY user_id HAVING MAX(date_assigned) BETWEEN '2015-05-01' + INTERVAL 1 DAY AND '2015-05-01' + INTERVAL 1 YEAR AND MIN(date_assigned) > '2015-05-01' + INTERVAL 1 DAY)

Answer 2

自我加入解决方案：在日期标准中找到最小值（第一次更改状态）：

select a.user_id,b.status_id,max(b.date_assigned) 
from user_status a
inner join user_status b 
on a.user_id=b.user_id 
and a.date_assigned <b.date_assigned 
where b.status_id >1 and a.status_id=1 
group by a.user_id,b.status_id 
having max(b.date_assigned)> '2015-05-01'
and max(b.date_assigned) <='2016-05-01'

MySQL：如何在特定日期之前选择具有最新日期的记录

2 个答案: