02. Databases

Goal

Understand how backend systems store and retrieve reliable data.

What to learn

• Relational model fundamentals.
• SQL essentials: SELECT, JOIN, GROUP BY, transactions.
• Schema design and normalization basics.
• Indexes and query performance basics.
• Intro to NoSQL tradeoffs.

Deliverables

• One relational schema for a real app idea.
• SQL scripts for core operations.
• Basic migration workflow.

Exit criteria

You can design tables for an application and write reliable queries for common product features.