mysql - 表行到mysql中的列

Question

假设我有一个类似于以下的数据库:

表events_degree:

event_id     degree_id
    1           1
    1           31
  ...           ...

表事件_区域:

event_id     area_id
    1           1
    1           31
  ...           ...

表events_schedule:

event_id     schedule
    1          Time 1
    1          Time 2
  ...           ...

表事件:

   id           name
    1           prom
    2         homecoming
  ...           ...

表度:

    id          name           shortened
    1     computer science        cs
    2      something else         se
  ...           ...              ...

表格区域:

    id          name
    1           hall 1
    2            gym
  ...           ...

建表:

    id          name
    1         main building
    2        second building
  ...           ...

我想做的是合并列，因为我有这个查询

SELECT `e`.*, `eh`.`start_date`, `eh`.`end_date`, `c`.`name` AS `degree_name`, `c`.`shortened` AS `shortened_degree`, `ai`.`name` AS `area_name`, `ed`.`name` AS `building_name` 
FROM `events` `e` 
LEFT JOIN `event_schedule` `eh` ON `e`.`id` = `eh`.`event_id` 
LEFT JOIN `event_degree` `ec` ON `e`.`id` = `ec`.`event_id` 
LEFT JOIN `degree` `c` ON `c`.`id` = `ec`.`degree_id` 
LEFT JOIN `event_area` `ea` ON `e`.`id` = `ea`.`event_id` 
LEFT JOIN `area` `ai` ON `ai`.`id` = `ea`.`area_id` 
LEFT JOIN `building` `ed` ON `ed`.`id` = `ai`.`building_id` 
WHERE `e`.`active` = '1' 
AND `eh`.`start_date` >= '2016-03-08' 
AND `eh`.`end_date` < '2016-07-01' 
ORDER BY `eh`.`fecha_inicio` ASC;

结果我得到了所有的行，正如你在图片中看到的那样

我怎样才能避免这种情况，谢谢你的帮助

** 注意 **这是同一个事件，所以它应该为每个事件只显示 1 行问题是我有 3 个多对多关系所以改变的只是日期、学位和地区

Answer 1

你可以使用 GROUP BY

SELECT DISTINCT `e`.*, `eh`.`start_date`, `eh`.`end_date`, `c`.`name` AS `degree_name`, `c`.`shortened` AS `shortened_degree`, `ai`.`name` AS `area_name`, `ed`.`name` AS `building_name` 
FROM `events` `e` 
LEFT JOIN `event_schedule` `eh` ON `e`.`id` = `eh`.`event_id` 
LEFT JOIN `event_degree` `ec` ON `e`.`id` = `ec`.`event_id` 
LEFT JOIN `degree` `c` ON `c`.`id` = `ec`.`degree_id` 
LEFT JOIN `event_area` `ea` ON `e`.`id` = `ea`.`event_id` 
LEFT JOIN `area` `ai` ON `ai`.`id` = `ea`.`area_id` 
LEFT JOIN `building` `ed` ON `ed`.`id` = `ai`.`building_id` 
WHERE `e`.`active` = '1' 
AND `eh`.`start_date` >= '2016-03-08' 
AND `eh`.`end_date` < '2016-07-01'
GROUP BY `your_id`;