Question

考虑以下MySQL表：

APPLICATIONS（包含所有用户的所有应用程序）

unique_id |  user_id  |  date_of_application  |  date_ended  | score  |  status
--------------------------------------------------------------------------------
1            user_a          2010-09-09          2010-12-24     1.2      Ended
2            user_a          2011-03-03          2011-06-06     1.3      Ended
3            user_a          2011-08-08          2011-10-10     1.0      Ended

4            user_b          2010-09-09          2010-12-24     2.2      Ended
5            user_b          2011-03-03          2011-06-06     1.5      Ended

6            user_a          2012-01-01                                  Active
7            user_b          2012-01-02                                  Active
8            user_c          2012-01-03                                  Active
9            user_d          2012-01-04                                  Active

期望的结果：

user_id  |  date_of_application  |  score  |  status
------------------------------------------------------
user_a          2011-01-01           1.0      Active
user_b          2011-01-02           1.5      Active

user_c          2011-01-03           10       Active
user_d          2011-01-04           10       Active

解释;我想选择/显示 status ='Active'的所有记录。此外，非首次申请者（user_a和user_b）的用户将其分数设置为上一个，最新一个（请参阅应用程序表中的粗体部分）'结束'status。另一方面，首次使用者（user_c和user_d）的分数将设为10。

注意/重申：

假设“已结束”应用/记录的分数始终正且不为空
user_c 且 user_d 第一次申请人
应用表会随着时间的推移有多个相同用户的记录，但用户一次只能拥有一个'有效'应用/记录

我有以下几点开始;这个（或类似的查询）给了我得分列

的NULL或0值


SELECT userid_, date_of_application, status,
score = 
(
     SELECT score 
     FROM applications
     WHERE status = 'Ended' AND 
           date_of_application = (SELECT MAX(date_of_application)
                                  FROM applications
                                  WHERE status='Ended')
)

FROM applications

WHERE 
status = 'Active'

ORDER BY 
score ASC,
date_of_application ASC

我在这里想念的是什么？ TIA。

Answer 1

考虑到你希望得分是基于最新的。试试这个 -

SELECT apps.user_id, apps.date_of_application, apps.status,
       IFNULL(
              (SELECT app.score 
              FROM applications app
              WHERE  app.user_id = apps.user_id
              AND app.status = 'Ended' 
              ORDER BY app.date_ended DESC
              LIMIT 1), 10) AS score
FROM applications apps
WHERE  apps.status = 'Active'
ORDER BY apps.score ASC,
         apps.date_of_application ASC

Answer 2

应该有效：

SELECT user_id, date_of_application, status, coalesce(latest.score, 10) score
FROM applications
LEFT OUTER JOIN 
  (SELECT user_id, score 
   FROM applications a
   WHERE status = 'Ended' AND 
         date_of_application = (SELECT MAX(date_of_application)
                                FROM applications
                                WHERE status='Ended' AND user_id = a.user_id)) latest 
                                  ON latest.user_id = applications.user_id
WHERE status = 'Active'
ORDER BY date_of_application ASC

从上一个最新记录中选择一列

2 个答案: