Database & Data Modeling Every SaaS app needs a database, and the schema decisions you make early are expensive to change later. This skill helps you choose the right database, design a clean schema, and set up security — explained without jargon. Core Principles - Choose the database that matches your hosting platform. Don't fight the defaults. - Schema design is product design. Get the relationships right early — migrations are painful later. - Every SaaS app is multi-tenant. Every table needs a way to isolate customer data. - Start simple. You don't need Redis, Elasticsearch, or a data war…