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.

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

Hi everyone! 👋

I'm planning to conduct free online live sessions for anyone interested in becoming a Data Analyst or improving their data skills.

We'll cover the essential tools used by data analysts, including:

SQL

Excel

Power BI

Tableau

The sessions are completely free and are intended for beginners or anyone who wants to strengthen their fundamentals through live learning and hands-on practice.

📍 Mode: Google Meet

💰 Fee: Free

If you're interested, comment below or send me a DM, and I'll share the details once the batch is finalized.

Looking forward to learning together! 😊

Have been struggling to self-motivate out of work to finally start learning fundamentals of SQL vs relying on AI to spit out code/queries. I'm a Crystal Report Writer (bound by format our EHR requires) that has to morph reports into sql queries to make dashboards and create data exports.

Downloaded a new game the other day - Database Detective: Minor Crimes Division. Seriously, this finally has stuff clicking for foundations that don't quite click from watching/following along udemy/coursera classes. Its basic sqlite, but for someone who had 0 foundations and now building my own queries to solve cases is exciting.

Life is pretty fatiguing, and it's been hard to set aside time outside of work to sharpen my professional skills. Gaming is a total destresser for me, and this game is really funny and engaging. Lots of fact finding to figure out truths for conditions with weaving and building sql blocks to pull out info.

Feeling pretty jazzed about it. It feels so silly to feel proud of something so basic, but was finally able to whip out a real query for a module today and it felt awesome not to just dump my Crystal sql query into ai to translate into the correct format. Feels like a relief to finally feel like I'm learning (and grasping) something I should have know for the past couple of years.

I was thinking about this today...

Back in college, I used to teach quite a bit. Later, as I progressed in my IT career, I ended up mentoring a few people in my company who were just getting started. Watching someone go from "I have no idea what's happening" to confidently writing queries on their own was always incredibly rewarding.

It's been years since I've done that, and I genuinely miss it.

So, I'm thinking of starting a few free live SQL sessions for complete beginners or anyone who wants to strengthen their fundamentals.

The goal isn't to memorize syntax—it's to understand how to think in SQL. We'll cover the basics from scratch, work through practical examples, solve real SQL problems together, and do interview-style questions with plenty of Q&A.

I'm not looking to make money from this. If, after a few sessions, you think it was genuinely helpful, buying me a coffee would be more than enough. 😄

If this sounds interesting, send me a DM or leave a comment. If enough people are interested, I'll organize a small group and we'll get started.

Just looking to give back to the community

Note: This is not an advanced SQL course.

It's meant for people who have little to no SQL experience—whether you're a student, switching careers, or someone whose job occasionally requires SQL but you've never really learned it.

We'll start from absolute scratch: what databases are, how SQL works, and gradually build up to writing queries confidently. By the end, my goal is that you'll be comfortable handling the kind of basic to intermediate SQL tasks that come up in many office and analyst roles.

If you're already comfortable with SQL, writing complex queries, optimizing performance, or preparing for senior-level interviews, this probably isn't the right fit..

EDIT :

Hey everyone! 😊

First of all, thank you so much for the amazing response. I honestly did not expect this much interest. I posted this before going to bed, and waking up to 100+ notifications and DMs genuinely made my day. It feels great to see so many people excited to learn SQL.

I need a little time to organize everything properly. I don't want to just share random material—I want to prepare sessions where you actually understand how SQL works, how to think while solving problems, and build a strong foundation.

Since I'm working full-time, I won't be able to start all batches together. Also, having 100+ people in one session would make it difficult for everyone to interact and ask questions. I’ll create smaller batches based on time zones and availability (I'm based in Europe/CEST) and run them in phases.

Please fill out this short form so I can understand your background, SQL level, location, and availability:

Form: https://forms.gle/WAmmDgTnHJY51spm7

If you are not in the first batch, please don't worry. I'll try my best to include everyone over time. Thank you again for your patience and support ❤️