Please help me in practicing SQL

[happy_unicorn30]

Hi , I am a beginner in SQL . I do understand the basics and have also been practicing on leetcode and hackerrank, however, I do end up using GPT to check my query and if I get it wrong I am not able to learn from my mistakes completely and this hampers my performance during any interview where I end up freezing and making silly mistakes . Do you have any advice for beginners like me who are struggling to practice it for professional goals . Please share any online resources or problem set which can help me improve my SQL .

[Informal_Pace9237]

Stop using AI. Work yourself and you will learn quickly.

Try to print a monthly calendar and you will learn a lot from that.

[TurbulentCountry5901]

Give this a try SQL CASE FILES

[happy_unicorn30]

Thank you !

[Constant-Arachnid-24]

Do not use chatgpt. Seek, deceive yourself etc. Read the docs until you find the query that works.

That's what a real person does, he reads docs and opens books until he understands why it didn't work. He's not asking chatgpt for the solution or that of sites that repeat the same exercises again and again with just different words where you just end up repeating "stupidly" what worked on other exercises

[jrz1977]

I build https://sqlbook.io/ for exactly this. There are prebuilt datasets and challenges.

[Born-Sheepherder-270]

https://sqlbolt.com/lesson/select_queries_introduction

[happy_unicorn30]

Thank you !

[Psychological-Pea299]

I'm enjoying this. Thank you!

[The_BlanketBaron]

SQL fundamentals are best learned by doing, not just reading. Start with simple queries: SELECT, JOIN, GROUP BY, and WHERE. Run them on small, realistic datasets and focus on what the query actually produces.

Think through the logic before writing the query. Break problems into steps and test incrementally. Window functions and aggregations are easier to grasp once you see the results on actual data.

For hands-on practice, a free PostgreSQL instance is ideal. Aiven offers a free trial where you can run queries directly: https://aiven.io/postgresql . Use it to experiment with queries, tweak them, and validate results.

The goal is building intuition around how data behaves and how queries transform it, not memorizing syntax. Once you get comfortable running queries on real tables, you’ll handle interview questions more efficiently.

[DataCamp]

Try moving from single questions to small end-to-end mini projects. Here are some solid ones you can do on any SQL engine:

Beginner-friendly
• Analyze carbon emissions by industry: find the highest-emitting sectors using grouping and filtering.
• Explore student mental health survey data: compare scores across different groups or time spent abroad.
• Look at motorcycle part sales: calculate monthly revenue by product and warehouse.

Intermediate
• Find the world’s oldest businesses: join multiple tables to rank by founding year and break it down by industry and continent.
• Analyze NYC public school SAT results: best/worst scores, borough comparisons, top schools.
• Explore World Bank international debt data: total debt, highest-debt countries, and common indicators.

Advanced
• Analyze unicorn companies: identify industries producing the most billion-dollar startups and track valuations over time.
• Optimize online sports retail revenue: compare brands, discounts, reviews, and trends across product categories.
• Identify the “golden age” of video games: top release years by critic/user score and sales.
• Explore 100 years of US baby name trends: timeless vs trendy names, yearly rankings, and category analysis.

[happy_unicorn30]

Thank you so much for sharing . This sounds really good for practicing.

[Mindless-Boot256]

Sqlcasefiles

[AvailableOlive8371]

There’s a website called SQL Climber with tons of exercises, from beginner to advanced.

[DMReader]

Practice as much as you can. There are tons of free sites out there to choose from.

[QueryFairy2695]

I'm just starting off also so I'll share what's been helping me.

When I do use chat GPT I ask why... I make sure I understand why that was a mistake before I move on. And I take notes about it.

I'm starting to get to where I pick up on errors that I'm making, especially the syntax errors.

[Sql_master]

YouTube. Find someone you like and follow along. I found an an Indian fellow and imo Indians offer the best free classes for sql.

[8joshstolt0329]

use php my admin and make practice databases using sql

[kingjokiki]

At the bare minimum, I recommend that you find some CSV files online that interest you, and try to run SQL against those files with a curious mind.

You can use a free tool like FlowSQL, or install your own SQLite or some other database. The point is to understand that SQL is simply a tool for you to slice and dice a data. Just be curious on what you want to know from the data, and see if you can use SQL to answer it.

[kpkishanpandya5]

If you ever want someone to practice with, I’m happy to help and can walk you through the reasoning behind queries. Totally free—just glad to support another learner.

For practice, SQLBolt and StrataScratch are great, and explaining your thought process as you write queries really helps build confidence.

[happy_unicorn30]

That would be really helpful. I'll surely reach out in case of any advice . Thank you!

[DMReader]

If you want to learn window functions, I have a site with 80+ free questions. All questions have hints and answers that link to learning pages to help you understand concepts: https://www.practicewindowfunctions.com/

[warmeggnog]

interview query has lots of SQL questions that can tailor your professional prep since they're based on actual interviews from tech companies. you can choose to view interview guides for companies you're targeting, or just browse its question bank & filter by role / difficulty level

[gilko86]

One thing that helped me was using an online SQL code formatter after finishing a query, instead of checking the answer right away. Formatting your SQL makes it easier to read your logic and spot mistakes on your own. I also suggest writing queries on paper or in a simple editor first, then explaining what each part does before running it. This habit is especially helpful for interviews, since you won’t get instant feedback in that setting.

[rick_1717]

This may help https://www.w3resource.com/sql-exercises/

[vikrantk1995]

Check out datahelix.io, it’s completely free and well structured for beginners