我怎样才能做这个多重 JOIN 查询？

Question

我需要构建一个包含多个 JOIN 的查询，更具体地说，是 2 个 JOIN，但它会得到重复的结果，请检查：

我当前的表：

食品商店

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 获取 *，从 categories_food_shops 获取 id_cat，从 pictures_food_shops 获取 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 与 categories_food_shops 的结果更多，所以我的结果是“四倍”：

我可以做些什么来防止这种情况并只获得正确数量的类别？ 第一行只有 1，第二行只有 3 和 5，最后一行只有 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。

Here is the documentation 和 DISTINCT 使用示例。