无法找出SQL查询

Question

In my database I have certain categories of food in a table called foodgroups. Therefore I have fooditems in a different table which relate to these categories. Moreover I created a table with orders called orders, and one "orderfood" table which defines the orders, in terms of how many of what products belong to an order.

My intention is to show the most sold fooditems in each category of food. So I want to get out one column with the categories and next to it a collumn with the fooditem which was most sold of the fooditems in this category.

Select  foodgroups.name, SUM(orderfood.fooditem_ID*orderfood.amount)

FROM    orders, orderfood, products, productgroups

Where   productgroups.productgroup_ID=products.productgroup_ID

AND     orders.order_ID=orderfood.order_ID

AND     products.product_ID=orderfood.product_ID

Group by productgroups.productgroup_ID` 

So far it doesn't show any errors, but I have no clue how to get a column with only the most bought food next to its category where it is the most bought one. Maybe you can help me, thank you :)

BTW, I am using the MySQL workbench.

http://sqlfiddle.com/#!2/4b79c/2

Answer 1

I think you're looking for the MAX function. Add it to your select statement

Select  foodgroups.name, SUM(orderfood.fooditem_ID*orderfood.amount), max(orderfood.amount)

FROM    orders, orderfood, products, productgroups

Where   productgroups.productgroup_ID=products.productgroup_ID

AND     orders.order_ID=orderfood.order_ID

AND     products.product_ID=orderfood.product_ID

Group by productgroups.productgroup_ID` 

That should return you the most ordered food