Mock SQL Projects

Introduction

Project-style exercises that mirror real work: build the schema, write the queries, optimize, and present trade-offs.

Understanding the topic

Core concepts to understand:

• Mini Stripe: payments + refunds + reports.
• Mini Slack: workspaces + channels + messages.
• Mini Twitter: users + follows + feed.
• Mini Airbnb: listings + bookings + reviews.
• Mini analytics: events + sessions + dashboards.

Syntax reference

Visual workflow / architecture:

Project plan
 1. ER diagram
 2. CREATE TABLEs + indexes
 3. Seed data
 4. Top 10 queries
 5. EXPLAIN + tune
 6. Document trade-offs

Real-world use

Hiring tasks at top companies often look exactly like one of these mocks.

Best practices

• Time-box yourself (4–6 hours).
• Document your decisions.
• Test queries against meaningful data.

Hands-on exercise

Interview preparation — practice these questions:

• Q1. Walk through your last DB project.
• Q2. Hardest decision in it.
• Q3. Numbers you measured.
• Q4. What you'd change.
• Q5. Production concerns.