Supabase is an open source Firebase alternative. Start your project with a Postgres database, Authentication, instant APIs, Edge Functions, Realtime subscriptions, and Storage.

Supabase

```const { data, error } = await supabase
  .from('countries')
  .select(`
    name,
    cities (
      name
    )
  `)
```

It's querying the countries and then its related cities base on the foreign key inside of the cities table

So it will return
```json
{
  "name": "The Country Name",
  "cities": [
    { "name": "The Name of City A" },
    { "name": "The Name of City B" },
   ]
}
```