SQL Preparation Part 2

Best Sites and Resources for Practicing SQL Interview Questions

Mastering SQL is crucial for aspiring data analysts, engineers, and scientists. Below are the most popular platforms and resources for learning and practicing SQL, from beginner to advanced levels, along with where you can find sample databases and datasets to support your journey.

1. LeetCode

• Platform: https://leetcode.com/
  Known for coding interview prep, LeetCode has a dedicated SQL section with interactive questions, sample databases, and discussion boards.

• Search for "Leetcode SQL practice" for Reddit threads with tips and problem recommendations.
  
  

2. HackerRank

• Platform: https://www.hackerrank.com/domains/sql

• Offers a range of SQL challenges from basic SELECT to complex joins and window functions.

• Provides in-browser sample datasets.

3. StrataScratch

• Platform: https://www.stratascratch.com/

• Focused on real-world problems (many asked by top tech and finance companies). 

• Problems come with sample tables and solutions, often recommended by the data community as "Leetcode for data guys."
  
  

4. DataLemur

• Platform: https://datalemur.com/

• Free platform with a paid upgrade, created by Nick Singh (Ace the Data Science Interview author). 

• Features interview-style SQL questions with sample databases. 

5. YouTube Channels

• Ankit Bansal’s Channel and others break down SQL interview questions and solutions step by step.
  
  

6. NamasteSQL (Paid)

• Platform: https://namastesql.com/ 

• 100 advanced SQL interview challenges to test your skills. 

• Paid access—recommended only if you’re confident with SQL basics and moderate problems.
  
  

7. DataCamp

• Platform: https://www.datacamp.com/ 

• Learn and practice SQL with exercises, tracks, and case studies (some content paid).

8. Other Popular Interactive Practice Sites

• Mystery Knight Lab 

• SQLZoo AdventureWorks 

• Codewars SQL

• 8 Week SQL Challenge 

• SQLPad (paid tier for interview-level problem sets)
  
  

9. Interview Query

• Platform: https://www.interviewquery.com/ 

• Cheaper than some competitors for paid content. 

• Focused on data-oriented interview prep. 

10. Practice with Sample Databases

Many DB platforms supply sample databases, ideal for exploring schema and trying real-world queries:

• Microsoft SQL Server: 

  • Sample Documentation 

  • Sample DB GitHub 

• MySQL: 

  • Employees Sample DB 

  • Sakila Sample DB
    
    

• PostgreSQL: 

  • Sample DB Wiki 

  • Samples on GitHub
    
    

• Oracle: 

  • Sample DB Manual 

• Generic: 

  • SQLTutorial Sample DB 

11. Free Datasets for Practice

Download raw datasets and design your own queries:

• Kaggle 

• FiveThirtyEight Datasets 

• Awesome Public Datasets 

• Wikipedia Datasets 

12. Third-Party & Tutorial Sample Data

• SQLSkills.com 

• SqlPracticeProblems.com — ~60 problems for practice. 

13. Live & Open Data Sources

Explore and use live datasets for advanced practice:

• Wikipedia Event Streams 

• Twitter API 

• [City Open Data portals: London, NYC, Seattle, Tokyo, Data.gov.uk] 

14. Discussion Boards

• Find platform and resource debates at
  Reddit: What's the best SQL practice platform? 

15. Widom’s SQL Practice Exercises

• Consider working through all SQL exercises in Widom’s SQL Tutorial.
  
  

Conclusion:
Whether you prefer interactive practice, tackling real interview questions, or exploring live/open datasets, the list above covers platforms for all skill levels. Be sure to choose paid platforms only once you’re confident with your SQL basics and core interview concepts.

Happy Querying!

Ashish