MySQL加入超过3个表

Question

我想根据感兴趣的用户位置获取事件，并留下用户不感兴趣的事件。我也试过但没有得到确切的事件数据。 根据此查询，如果uninterested_event表中没有记录，则不从表中获取记录。

> SELECT * FROM `event` e JOIN `user_interested_location` uil ON
> e.`city` = uil.`city` AND uil.`user_id` = 'A' JOIN
> `uninterested_event` ue ON e.`event_id` != ue.`event`
> AND ue.`user_id` = 'A' WHERE e.`start_date` >= '2018-04-14' ORDER BY
> e.`start_date` ASC



--------------------
    Event table
--------------------

event_id  | event_name | city   | start_date
event_1   |   event1   | kanpur |  2018-04-15
event_2   |   event2   | Noida  |  2018-04-20
event_3   |   event3   | Delhi  |  2018-04-14
event_4   |   event4   | Kanpur |  2018-04-17


--------------------------------
 user_interested_location table
--------------------------------

user_id  |  city   | 
   A     |  kanpur |
   B     |  Noida  |
   A     |  Noida  |


-----------------------------
 uninterested_event table
-----------------------------

user_id  | event_id | 
   A     |  event_1 |
   B     |  event_2 |


 ------------------------------
      output (user_id for A)
 ------------------------------

event_id  |  user_id   | city   | start_date
event_4   |   event4   | Kanpur | 2018-04-17
event_2   |   event2   | Noida  | 2018-04-20

Answer 1

试试这个：

loadData()