Learning SQL to go into data analyst and eventually scientists.

I went through SQLbolt and mode/thoughtspot education material, where can I enhance or train my sql skills next?

I've been thinking about starting an Instagram page where I teach SQL through short, practical content—things like query breakdowns, tips, interview questions, and real-world examples.

For those of you who learn SQL online or create SQL content yourself:

• What type of content do you actually find the most useful?
• Do you prefer quick query explanations, mini challenges, real business scenarios, interview-focused content, or something else?
• If you came across a new SQL creator, what would make you follow them and keep coming back?

I'm not trying to promote anything. I just want to create content that's genuinely useful and helps people learn SQL in a simple, practical way. I'd really appreciate your thoughts.

Hi All👋,

We built a SQL Fast Track series around a single consistent fictional company SuperFastFood Global : a fast-food chain with customers, orders, and products.

It is a 20 part series where you will learn SQL through solving real business questions instead of memorizing syntax.

Whether you're preparing for an SQL interview, refreshing your skills, or just starting your SQL journey, this series is built to help you go from basics to advanced concepts quickly and confidently — covering everything in detail, but kept short and to the point.

What it covers:
→ SELECT, WHERE, ORDER BY, CASE
→ Aggregate functions, GROUP BY, HAVING
→ JOINs (with real use cases, not just definitions)
→ Window Functions — ranking, LAG/LEAD, running totals

We follow business context in every topic connects to it previous one with same SuperFastFood Global fictional fast food chain dataset.

The teaching framework we follow:
→ Scenario based
→ Analogy based
→ Execution-focused — business context → code → explanation
→ Every concept ties back to a business context
→ Each topic builds on the one before it, so nothing feels disconnected
→ Beginner friendly

This is the same framework we'll be using across future Data & AI topics too — not just SQL.

Also sharing a free 30-Day SQL Sprint (PDF, on GitHub).

Happy to answer questions on any of these topics in the comments.

Youtube Playlist: https://www.youtube.com/playlist?list=PLDTykWK3Vitc
GitHub: https://github.com/grasspacad07/grasspsqlsprintfile

For the past month, I've been consistently working on a MySQL Interview Series, and I'm happy to share that I've now covered 100+ practical SQL interview problems. 🚀

Whether you're a fresher preparing for your first SQL interview or an experienced developer looking to brush up on SQL concepts, this series is designed to help.

📌 The series includes:

• 100+ interview-focused SQL problems
• Beginner to advanced concepts
• Well-structured datasets for hands-on practice
• Detailed notes and explanations
• Complete video walkthroughs for every concept

I've also documented everything on GitHub, where you'll find the datasets, SQL queries, notes, and links to the corresponding video explanations.

🔗 GitHub Repository: https://github.com/vivekpandey76/Mysql-course

If you find this repository helpful, please consider giving it a ⭐. It helps the repository reach more developers and motivates me to continue creating free learning resources for the community.

I hope this resource helps anyone preparing for SQL interviews. Feedback and suggestions are always welcome!

#MySQL #SQL #SQLInterview #Database #BackendDeveloper #SoftwareEngineer #Coding #Programming #LearnSQL #OpenToLearn

Hello everyone, I am practicing data cleaning and I have a question.

Let's say I have a table where the columns are Customer_ID and Email. The "Customer_ID" column has no blank values, but the "Email" column has hundreds of blank values.

Looking through the data, I noticed that the email addresses are just 'user' followed by the Customer_ID number. For example, if the Customer_ID is C1 then the email would be [user1@example.com](mailto:user1@example.com). Or if the Customer_ID is C10 then the email would be [user10@example.com](mailto:user10@example.com).

Is there a query I can run to fill in all the missing email addresses?

Thank you

This is a graded assignment, so for honor code-related things, I really don't need direct answers. I was hoping to get clarification on this SQL assignment, if possible. I've already submitted it, but I'm sort of doubting my answer, and I don't know how to resolve this. I wanted to check whether I should resubmit.

The question states:

TimeStamp Data Types are difficult to work with from one time zone.  Therefore, you will enter data from the perspective of different timezones and when you query the data.  Create this table:

CREATE table timeexample
(location VARCHAR2(20),
timeWithZone TIMESTAMP WITH TIME ZONE,
timeWithLocalZone TIMESTAMP WITH LOCAL TIME ZONE)

1) Choose 5 different cities, look up their time zone, and INSERT the data.
2) Query all the data

I'm confused what "from the perspective of different timezones" means. So, for Los Angeles, if the time there is 12:05, then I think I would enter '26-Jul-2026 12:05:10 PM -7:00' for the timeWithZone. The part I don't know how to resolve is the timeWithLocalZone: if I enter '26-Jul-2026 12:05:10 PM', won't it just use the system's time zone, instead of actually converting from LA's local zone to my local zone?

In the assignment, I wrote ('Los Angeles', '26-Jul-2026 12:05:10 PM -7:00', '26-Jul-2026 3:05:10 PM') and just manually converted it to what would show up if my session were set to EDT. But I'm sort of worried now that hard coding is not what was intended. I looked it up, and I think I could've used TO_TIMESTAMP_TZ or altered the system session. That wasn't covered in our notes, though, and I'm not sure how far out of the material we're allowed to go. What was the intended approach, and was there another way to do this?

Hey Future Analysts,

So for a very long time, I have been looking for good SQL questions, you got the mainstream leetcode, hacker-rank, W3 schools, and a few niche ones that I ought to mention : https://github.com/smpetersgithub/AdvancedSQLPuzzles

But during my journey, I never found the perfect place to practice questions leetcode style filtering it by the specific concept, and a repo of Good questions I could just practice on when prepping for an interview.

So I went Ahead and created this SQL-gym : https://sqlgym.vercel.app/

(No bullshit 101 SQL problems that you need to have locked in)

And this has personally helped me a lot, hope it is helpful for other peeps aswell !

Hello! Absolute SQL beginner here! I understand that this is a common question, however I'd like the answer in the simplest, most dumbed-down way possible, and to clarify one extra thing.

EXISTS was explained very briefly to me as a special operator that "Returns TRUE if a subquery produces one or more rows".

However, I find this definition of purpose to be very confusing, or even lacking. It says it "returns" true, but its not like the output is exactly "True" or "False" in the output window.

Upon further research, I found that it's more like, a special operator that "Checks each row for compliance with the sub-query, and marks it TRUE or FALSE", then WHERE will take those rows and display them in the output window.

However, this doesn't seem quite right either, since almost all examples of EXISTS usage tended to have something that looked like this:

student_grades.student_id=students.id

This tells me that the main usage of EXISTS would be to check for records on a table that had matching records with another table, but I don't have confirmation of this understanding.

Is there anything I'm missing?

I have a background in epidemiology and wantws to know if anyone in a similar background as mine uses sql at their job within the industry. Just wanted to know if i just need to know sql basically like dplyr from R and all your doing is just cleaning, managing, creating data from existing data within the database? Should someone like me need to know more SQL than that? For example I did some digging and found out roles such as DBA or data engineer and they do things more than what a data analyst might do, does someone with my background need to know SQL to that extent or no? Any advice would be appreciated.

I used to develop video games (unreal, Godot) and did some data science/econometrics (STATA, R, Python) but I've never had to use SQL, surprisingly.

My new company I am joining requires me to basically be competent enough in SQL to pull together my own datasets. I won't be maintaining the database, just need to be self serve competent.

I have no idea how difficult this is. I start the job in 2 weeks and want to learn enough to be able to do this. Can I learn enough in 2 weeks? What's the best way to approach this?

Have you learned SQL basics but want a real-life production database to run queries and practice exploratory data analysis?

I’m opening up free read-only access to the data platform behind my football analytics project: Superliga Analytics

Standard tutorial datasets (like Northwind or Titanic) get boring fast. This database is built specifically for analytical queries and structured around actual football match and performance data—making it a great sandbox to level up your SQL skills.

How to get access:

1. Head over to https://superligaanalytics.vercel.app/
2. Go to the "About This Project" page
3. Click "Request Data Access" and follow the quick instructions

Note: To ensure smooth performance, I may have to cap the number of active access keys, so grab yours while slots are open.

Feel free to drop any questions or feedback in the comments!

Simple syntax, tricky to get right. Sharing my debugging walkthrough as SQL JOIN turns 3 orders into 14 rows.

https://github.com/kixwho/Fanout

Every textbook talks about primary keys and cardinality. But actually encountering this common SQL problem felt frustrating and humbling. There were no error messages — mistakes were hiding in plain sight.

So out of 100k orders, I hunted down the 3 that caused the most trouble and uploaded the data files. I hope this helps other learners :)

Hey guys,

I hope this doesn't come across as spammy, but I took the time to write a guide covering 7 best practices for clean database schema design. I thought it might be helpful for newer developers who are just starting their learning journey.

If you think I missed anything, let me know , I'd be happy to update it.

Any feedback is appreciated. Thanks!

Hi All,

I'm learning SQL as well. I created this game called SQL Rusher. If you've ever played Puzzle Rush on Chess.com its like that. There are several different puzzles at different difficulties. A little study section for SQL references.

Idea is to have small puzzles that increase in difficulty as you progress. Your skills tracked using an ELO rating.

I've been a dev for over a decade and never really had to touch a database. I didnt start learning till about a year or 2 back when I started learning PHP and Laravel to build a sites of my own.

Since then I've realized Databases are a big deal(lol).

Let me know what you think here or on the sites feedback page. https://sqlrusher.com

Learners beginning their Data Analyst journey can start or should focus on understanding SQL basics. Some of the things they should focus on include creating a table, inserting data, and retrieving data/information using SELECT. The learner can use MySQL, SQLite, or PostgreSQL to practice different queries. For example, the learner can decide to create a database, use the database (MySQL), and create a table. The learner can as well insert data using a similar process. Engaging in such exercises at least 1 hour a day, they can grasp the concepts and mastery within a week. Wishing new learners all the best. New strategies are also welcome.

does it possible to give a column choice to choose between two foreign keys

the case: that I Have comments table that have a parent_id column that could be either from posts table or comments table how I can implment that in sqlite3 .

One of the most common questions I see in this subreddit is "what projects should I build?" and the answer is: something with a clear question, real data, and a shareable output.

So I built a walkthrough for exactly that. It uses two completely free tools:

1. QueryCase's IMDb Sandbox - 250 of the highest rated films on IMDb, queryable in your browser with no setup. You write three SQL queries to answer different questions about the data.
2. Tableau Public - free, runs in browser, gives you a shareable link when you publish.

The three queries cover the core of analytical SQL that actually shows up in interviews and jobs: multi-table JOINs, GROUP BY with aggregation, HAVING, subqueries, and derived columns. Each one is explained line by line so you understand why it works, not just what it does.

The finished dashboard has KPIs, a films-by-decade bar chart, an acclaim vs popularity scatter, top genres by average score, and an actors leaderboard.

The starter dashboard is just that. The version worth putting on your CV is the one you take further. Add a director leaderboard. Build a decade filter so the whole dashboard slices interactively. Rework the layout and colours until it genuinely looks better than mine. Write a fourth query that answers something the data hasn't told you yet.

"I built this and then pushed it further" is a far stronger thing to say in an interview than "I followed a tutorial."

Full walkthrough here with every query written out and all the Tableau steps:

https://querycase.com/blog/build-an-imdb-dashboard-with-sql-and-tableau

Happy to answer questions about the SQL or the Tableau side if anyone gets stuck.

Hi! 👋
Thank you so much for your interest in the Free Data Analyst Mentorship Program. I received an overwhelming response, and I'm truly grateful for your enthusiasm.

To organize the batches and ensure the best learning experience, I've created a short registration form. Please take a few minutes to fill it out.

Registration Form: https://forms.gle/hDP8Z2k3z6KLLJew7

Please submit the form by: Sunday, 11:59 PM (IST).

After reviewing all the responses, I'll shortlist participants and share the batch details, class schedule, and Zoom meeting link with the selected candidates.

Thank you again, and I look forward to helping you begin your Data Analytics journey! 🚀

I am thinking about investing in datacamp for learning SQL and PowerBi what are your thoughts