我怎么能做这个多JOIN查询？

Question

我需要使用多个JOIN构建一个查询，更具体地说，2个JOINS，但它会得到重复的结果，请检查：

我目前的表格：

food_shops

id, slug, name

categories_food_shops

id, id_cat, id_food_shop

pictures_food_shops

id, pic_slug, id_food_shop

我需要从food_shops获得*，来自categories_food_shops的id_cat和来自pictures_food_shops的pic_slug ......

我目前的查询是这样的：

SELECT food_shops.id, food_shops.slug, food_shops.name, 
GROUP_CONCAT(categories_food_shops.id_category) as categories, 
GROUP_CONCAT(pictures_food_shops.slug) as pictures 
FROM
food_shops 
JOIN categories_food_shops 
    ON food_shops.id = categories_food_shops.id_food_shop 
JOIN pictures_food_shops 
    ON food_shops.id = pictures_food_shops.id_food_shop 
GROUP BY food_shops.slug, pictures_food_shops.id_food_shop

但由于我的pictures_food_shops作为categories_food_shops有更多的结果，我的结果是“四倍”：

我该怎么做才能防止这种情况并获得正确数量的类别？ 第一行只有1，第二行只有3和5，最后一行是7,1,6？

谢谢！

Answer 1

你可以试试这个：

...
GROUP_CONCAT(DISTINCT categories_food_shops.id_category) as categories, 
....

这也适用于图片。

使用DISTINCT使用示例

Here is the documentation 。