📖 Quick Navigation

SQL 50 - Master Database Querying 🗃️

Transform your SQL skills through 50 carefully curated problems using research-backed active learning methodology.

🎯 Why SQL 50?

SQL is the universal language of data. Whether you’re a software engineer, data analyst, or business professional, SQL mastery opens doors to powerful data insights. Our SQL 50 collection provides a structured path from basic queries to advanced database operations.

📊 Study Path Overview

🌱 Foundation (Week 1-2)

Basic Queries

8 problems • SELECT, WHERE, DISTINCT

Beginner

Sorting & Aggregation

8 problems • ORDER BY, GROUP BY, COUNT, SUM

Beginner-Intermediate

🚀 Core Skills (Week 3-4)

Joins

9 problems • INNER, LEFT, RIGHT, FULL OUTER

Intermediate

Subqueries

7 problems • Nested Queries, EXISTS, IN

Intermediate

String & Date Functions

6 problems • String Manipulation, Date Arithmetic

Intermediate

🏆 Advanced (Week 5-6)

Window Functions

8 problems • ROW_NUMBER, RANK, LEAD/LAG

Advanced

Advanced SQL

4 problems • CTEs, CASE, UNION, Complex Queries

Advanced

🧠 Active Learning Methodology

Research-Backed Approach

Based on “Stop Building AI Tools Backwards” principles, each problem promotes genuine learning through:

🤔

Think First

Schema analysis and reflection questions before seeing solutions

💡

Guided Discovery

Step-by-step query construction through progressive disclosure

🎯

Practice & Assessment

Implementation challenges and confidence tracking

🔗

Pattern Recognition

Connect SQL techniques across problems and real-world scenarios

📈 Progress Tracking

Mastery Indicators

  • ✅ Can write queries without reference
  • ✅ Can explain query logic clearly
  • ✅ Can optimize for performance
  • ✅ Can adapt solutions to variations

Study Schedule

  • Daily: 30-45 minutes, 2-3 problems max
  • Weekly: Review previous problems
  • Biweekly: Practice with real datasets

🛠️ Database Platforms

All examples use standard SQL compatible with:

  • MySQL (primary examples)
  • PostgreSQL (alternatives noted)
  • SQL Server (platform-specific tips)
  • SQLite (lightweight practice)

🚀 Quick Start Guide

1. Set Up Practice Environment

-- Option 1: MySQL (Recommended)
-- Download from mysql.com

-- Option 2: Online SQL Playground
-- Use sqliteonline.com or db-fiddle.com

-- Option 3: PostgreSQL
-- Download from postgresql.org

2. Start Learning

  1. Begin: Basic Queries Guide
  2. Practice: Work through problems systematically
  3. Reflect: Use confidence ratings to track progress
  4. Connect: Join study groups or forums

3. Build Real Projects

  • Analyze your own data
  • Create business dashboards
  • Contribute to open-source projects
  • Build portfolio projects

🌟 Success Stories

“The guided discovery approach helped me understand not just HOW to write SQL, but WHY certain patterns work. The confidence ratings kept me honest about my actual understanding.” - Sarah, Data Analyst

“Finally, SQL tutorials that don’t just give you the answer! The schema analysis sections really changed how I approach database problems.” - Mike, Software Engineer

🔗 Additional Resources

Learning Support

Community

🎯 Ready to Start?

🚀 Start with Basic Queries 📚 Read Full Documentation

Master SQL through active learning and guided discovery. Your data journey starts here! 📊