MySQL:多行以逗号分隔的单行

Question

我有两张桌子:DISH和DISH_HAS_DISHES.菜桌上有所有的菜肴,"Dish_has_dishes"表与"菜"表有一对多的关系.即一道菜可以有多道菜.例如

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

这里的meal_id和dish_id都是来自DISH表的ID.现在我想要一个这样的格式:

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

这是逗号分隔的菜肴ID和每餐的名称.怎么做？

Answer 1

使用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