Products in Each Order
Medium · Strings
string_agg(value, separator) joins the values of a group into one text. Put an ORDER BY inside the call to control the order of the pieces: string_agg(name, ', ' ORDER BY name).
For every order that has items, return order_id, products (the product names joined with ', ', in alphabetical order) and total_quantity (sum of quantity). Sort by order_id.