Lesson 17 — Relations

Records that point to other records

A foreign key is a field that stores the id of a record in another table. An order does not copy the user's name; it stores uid: 1, and you look up user 1 when you need the name. In Django: order.user.name.

cities = {7: "Almaty"}
cities[shop["city_id"]]   # 'Almaty'

Note: the exercise runs in your browser without Django installed, so it is a small plain-Python simulation of what Django does for you.

Why it matters: storing the name once means changing it once — every order shows the new name.