How to fill table with Dropdown select?

I need a Project for school based on PHP and HTML with integration of SQL DB. We've got a DB with 2 tables: The first table contains shopId and shopName e.g.

shopId       shopName
1            McDonald's
2            Burger King
3            KFC

and the 2nd table contains productId, prodName, price and shopId from above:

prodId       prodName        price        shopId
1            BigMac          2$           1
2            Whopper         3$           2
3            Long Chicken    3$           2
4            Hot Wings       5$           3

Now I've created a HTML select/dropdown and filled it with the shopName. What should happen is: When I select a shop from the Dropdown, a HTML table below should fill up with the products which are available in the respective shop.

I hope someone could help me with that! I'm pretty new to PHP but our group doesn't care about that..