Orders

The shop's database holds more than products. The table orders has one row per order: its id, the customer_id of the customer who placed it, the date it was placed (ordered) and its status. The customer's name is not in that row: it lives in another table, customers.

A JOIN reads two tables in one query. Its ON condition says which rows belong together, and table.column says which table a column comes from. Here is the idea on two other tables, books and their authors, with the query written in pieces joined by +:

query := "SELECT books.title, authors.name AS author " +
    "FROM books " +
    "JOIN authors ON authors.id = books.author_id"

Each book is paired with the one author whose id is the book's author_id. AS author renames the column in the result of this query. + adds nothing between the pieces, so end each piece with a space. Scan fills a struct's fields in the order of the SELECT's columns, and the JSON keys come from the struct's tags.

Your handler must give these answers:

GET /orders/1   →  200  {"id": 1, "ordered": "2026-03-02", "status": "paid", "customer": "Ana Pop"}
GET /orders/4   →  200  {"id": 4, "ordered": "2026-04-18", "status": "shipped", "customer": "Chloe Ng"}
GET /orders/6   →  200  {"id": 6, "ordered": "2026-05-21", "status": "cancelled", "customer": "Ben Ortiz"}
GET /orders/99  →  404  {"error": "Order not found"}

Your task: the Order struct and an empty handler for GET /orders/{id} are already in the file. Fill the handler: read the order and its customer's name with one JOIN query and answer them as JSON, or 404 when no order has that id.

Assignment
Follow the Coding Tutorial to fill the GET /orders/{id} handler and its JOIN query.

Hint
Both tables have a column id, so write orders.id or customers.id, never just id. Scan gives back sql.ErrNoRows when no order has that id, as in the GET /products/{id} handler.