A comprehensive collection of SQL solutions and explanations for HackerRank problems, organized by difficulty and topic to help developers master database querying skills.
This repository contains solutions to SQL problems from HackerRank, designed to help developers improve their database querying skills. Each solution includes detailed explanations, multiple approaches where applicable, and best practices for writing efficient SQL queries.
Whether you're preparing for technical interviews, improving your database skills, or simply looking to master SQL fundamentals, this repository provides structured practice with real-world problem-solving scenarios.
- Basic understanding of SQL syntax and database concepts
- Access to a SQL database system (MySQL, PostgreSQL, SQLite, SQL Server, etc.)
- Text editor or SQL IDE (MySQL Workbench, pgAdmin, DBeaver, VS Code)
- Git installed on your local machine
- A HackerRank account for accessing original problem statements
- Clone the repository:
git clone <url>
cd repo -
Choose your preferred SQL environment and set up a practice database
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Navigate to any problem directory to view solutions and explanations
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Test solutions using your preferred SQL environment
Fundamental SELECT operations, filtering, and data retrieval
- Revising the SELECT Query
- Select All
- Select By ID
- Japanese Cities Attributes
- Weather Observation Station series
Complex conditional logic and data transformation
- Type of Triangle
- The PADS
- Occupations
- Binary Tree Nodes
- New Companies
GROUP BY operations and aggregate functions
- Revising Aggregations
- The Count Function
- The Sum Function
- Averages
- Population Census
- Population Density Difference
Table relationships and JOIN operations
- Population Census
- Asian Population
- African Cities
- Average Population of Each Continent
- The Report
- Top Competitors
Complex multi-table operations and advanced JOIN techniques
- SQL Project Planning
- Placements
- Symmetric Pairs
- Interviews
- 15 Days of Learning SQL
Pattern generation and advanced problem-solving
- Draw The Triangle patterns
- Print Prime Numbers
- W3Schools SQL Tutorial - Comprehensive SQL reference and tutorials
- SQLBolt Interactive Lessons - Interactive SQL exercises for beginners
- PostgreSQL Documentation - Official PostgreSQL documentation
- MySQL Documentation - Official MySQL documentation
- SQL Server Documentation - Microsoft SQL Server resources
- HackerRank SQL Domain - Original source of these problems
- LeetCode Database Problems - Additional SQL challenges
- SQLZoo Interactive Tutorial - Interactive SQL learning platform
- Codecademy SQL Course - Structured SQL learning path
- SQLiteOnline - Browser-based SQL practice environment
This project is licensed under the MIT License. The problems are property of HackerRank and are used here for educational purposes only. Solutions are provided to help with learning and should not be used to cheat on actual assessments.
Remember, the best way to learn SQL is through consistent practice and understanding the logic behind each query.