Check: databases in an app | ComputeSphere Learn

Goal: Confirm you can read a relationship in a schema, predict what a migration run does, and keep connections under a database's limit.

Four questions: three on this module, one on Module 1. Every answer explains itself, right or wrong.

A shop has customers and orders. Each order belongs to one customer, and a customer can place many orders. Which column makes that link?orders.customer_id, a foreign key to customers.idcustomers.order_id, a foreign key to orders.idorders.id, the primary key

A teammate added a column to production by hand in the SQL console. Next release, the migration that adds the same column fails. What went wrong?The change skipped the migrations, so production and the migration record disagreeThe migrations ran in the wrong orderMigrations can't add columns to production

Your database allows 100 connections. Your web service runs 6 spherelets with a pool of 20 each. What happens as the sixth spherelet starts?Connections are refused, and requests start failingNothing: the spherelets share one pool of 20The database slows down but serves everyone

From Module 1: a teammate wants the signup page's JavaScript to write straight to the database, to save building an API. Why won't that work safely?The browser would need the database password, and anyone can read itBrowsers are too slow to talk to databasesThe database needs a different schema for browsers

Retry as often as you like.