MySQL的檢索多對多行

Question

當我火了下面的查詢，我得到我需要通過event.id分組的結果：

SELECT events.id AS id,events.name AS event,categories.name AS categories 
       FROM events,categories,event_dates,event_categories 
       WHERE events.preview = 0 AND event_dates.start_date > DATE(NOW()) 
        AND events.id = event_dates.event_id AND events.id = event_categories.event_id AND event_categories.category_id = categories.id 
       GROUP BY events.id LIMIT 0,5 

結果如下（event_categories是鏈接事件類別表） ：

Array ([id] => 144 [event] => Twickenham Stadium Tours and World Rugby Museum [name] => Sport) 

但是，這是一個多對多的關係，這個查詢只返回一個類別。如何將這種重新排列/編制一個查詢，會抓住所有類別

Answer 1

嘗試在查詢中使用group_concat

GROUP_CONCAT(DISTINCT categories.name ORDER BY categories.name SEPARATOR ",") 
AS categories 

等等之類的最終查詢：

SELECT events.id AS id,events.name AS event, 
GROUP_CONCAT(DISTINCT categories.name ORDER BY categories.name SEPARATOR ",") 
    AS categories 
       FROM events,categories,event_dates,event_categories 
       WHERE events.preview = 0 AND event_dates.start_date > DATE(NOW()) 
        AND events.id = event_dates.event_id AND events.id = event_categories.event_id AND event_categories.category_id = categories.id 
       GROUP BY events.id LIMIT 0,5