MySQL：多行以逗号分隔单行 [英] MySQL : Multiple row as comma separated single row

问题描述

我有两个表：DISH和DISH_HAS_DISHES。菜盘有所有菜，Dish_has_dishes表与菜表具有一对多的关系。也就是说一个菜可以有多个菜。例如

I have two tables : DISH and DISH_HAS_DISHES. Dish table has all the dishes and "Dish_has_dishes" table has a one-to-many relationship with "Dish" table. I.e. a dish can have multiple dishes. For example

DISH ：

dish_id   dish_name
1         dish_1
2         dish_2
3         dish_3
4         dish_4

DISH_HAS_DISHES ：

meal_id   dish_id
1         2
1         3
1         4

这里，meal_id和dish_id都是DISH表中的ID。现在我想要这样的格式：

Here meal_id and dish_id both are IDs from DISH table. Now I want a format like this:

meal_id     dish_ids     dish_names
1           2,3,4        dish_2, dish_3, dish_4

这是以逗号分隔的菜单ID和每餐的名称。如何做？

That is comma separated dish id and names for each meal. How to do that?

推荐答案

使用GROUP_CONCAT FUNCTION

Use GROUP_CONCAT FUNCTION

http://dev.mysql.com/tech-resources/articles/4.1 /grab-bag.html

 SELEct m.meal_Id, 
        GROUP_CONCAT(dish_id) dish_ids, 
        GROUP_CONCAT(dish_name) dish_names
 FROM DISH_HAS_DISHES m JOIN DISH d ON (m.dish_id = d.dish_id)
 GROUP BY meal_Id

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