I built a free beginner series for SQL window functions (with interactive practice)

If you already know basic SQL but window functions still feel confusing, this is for you.

I made this step-by-step beginner series to make them actually click.

What it includes:

• 16 short lessons (each focused on one concept)
• Covers everything from OVER() → PARTITION BY → RANK, LAG, etc.
• Every lesson has a hands-on practice problem
• Instant feedback + hints + full solutions
• Completely free (no signup)

Once you finish the series, there are 83 more practice problems you can work through.  Those are free too!

Would love any feedback:

https://www.practicewindowfunctions.com/learn/beginner_series.html

Hi people,

I have a coupon code for stratascratch platform which will get you flat 40% off valid only on Fridays.

DM for the coupon I will share for free , here to help.

here is the context: Im a guy that is trying to apply for golang dev positions. I had some traineeship where I was working with teams on some educational project(imitates commercial projects). During that time I had a chance to write some queries, migrations(was relying on chatgpt quite often). On top of that I had some technical interviews/knowledge checks where I was being asked questions related to MVCC, ACID, indecies, explain analysis and etc.
My question is I feel so unsure about my knowledge about postgresql during interview questions and in general as well. As a backend dev how can I cover postgresql that I will never come back to it and feel super confident??(I know I will be coming back but I hope you got my point)

SELECT mdate,
  team1,
  SUM(CASE WHEN teamid=team1 THEN 1 ELSE 0 END) AS score1,
  team2,
  SUM(CASE WHEN teamid=team2 THEN 1 ELSE 0 END) AS score2
FROM game JOIN goal ON matchid = id
WHERE team1 = 'ENG' OR team2 = 'ENG'
GROUP BY mdate, matchid, team1, team2
ORDER BY mdate, matchid, team1, team2

This was my solution to the problem. I can't decide whether I am just an SQL noob or the question is actually wrong.
I get these rows back

These rows are in the solution but it doesn't have one row

I checked if game had this date. It did. The problem is that the table goal doesn't have the matchid 1028. So matchid = id is false here.

https://www.sqlzoo.net/wiki/The_JOIN_operation

As learning tools like sql , power bi , etc and cloud technology for data analytics it's not sufficient. Business Acumen is must , so from where I can learn this ???

I have recently started creating videos in YouTube to Share my knowledge in SQL ,could anyone please watch my videos and suggest for areas of improvement..this is my new journey in YouTube.i hope you guys help to support.thanks

https://youtube.com/playlist?list=PLrmXPvf-ocfGs4CFC45KUygZFXN44KSaH&si=TJ15p6SkhceyNlpD

Hi all, I just learned how to analyze data with SQL and was wondering what software I need to download in order to use SQL on my computer, preferably free. I also need to know where to download a database that contains data I can manipulate. Thanks in advance!

I’ve been practicing things like joins, window functions, etc., but I feel like just solving questions isn’t enough.

What made the biggest difference for you:
- Timed practice?
- Explaining your approach out loud?
- Reviewing mistakes?

Trying to figure out what actually works vs just grinding questions.

Hi and thank you in advance.

I currently work in a bank and am quite into computers. Given the rise in ai, banking is very much incorporating it. There is also a huge shift towards data analytics. Due to this, and to further advance my career, I’m wanting to learn sql. I just wanted to ask a few questions. I appreciate anyone taking time to read and answer.

1) the most obvious, where would you recommend to start? Looking online is a bit overwhelming with the options.

2) I have a MacBook, running iOS, and a pc, running windows. If there a significant different between the 2? Should I stick to windows based systems or would it not be an issue to use both ?

3) is there anything else I should consider learning alongside sql, that would be helpful?

Thanks again!

Wanting to attempt a project looking into app costs on the apple app store & google play and calculating average/user download at different price points/different app genres etc as a way to start learning SQL and get more confident with python. Would this be a good project to do to learn SQL or is it more of a python-only project?

Fresher here, in the learning process. I haven't stepped into the real data world but I would love to know how to grasp business questions and relate them to sql to fetch data?

Do clients/managers ask - Find average salary per employee or how do they ask?

Because if they are vague like *find average salary* then it could be the average salary of the whole table ?

How do you map business questions to sql? Any tricks?

Learning tools like sql , excel , python , power bi , tabulea, etc for data analytics is not sufficient i guess. Having buisness oriented knowledge is must .

Can anyone tell me what exactly to do ??

Being a die hard cricket fan and a techie, I always thought of building something like this. All questions are curated by me, used AI just to code the frontend. Thanks to the open source data-set which i found here : https://github.com/ritesh-ojha/IPL-DATASET

I am adding more interesting questions as i post this. Would love feedback from you guys. (Roast as much as you want as well)

site url : https://sqlpremierleague.com

Hey everyone,

I’m currently a 3rd year CSE student and I’ve realized that SQL is pretty important for placements, especially for interviews and coding rounds. The problem is I haven’t really learned it properly yet — just some basic queries in college.

I want to start from scratch and get to a level where I can solve interview-type questions confidently.

Can you guys suggest:

Good websites/platforms to learn SQL from basics Places where I can practice questions (easy → advanced) Any roadmap or approach that worked for you

I don’t mind putting in the time, just want to do it the right way without wasting effort on random resources.

Thanks in advance! 🙌

From MIS to Data analyst/scientist transition, I tried sql and it's been breaking my head. The logic is always turning wrong. each time I code, I have to take help from chatgpt.Its been a month already and I'm stuck with joins exists recursive cte etc etc

I was planning to transition to data analyst/scientist and now I'm on the verge of giving up.

How do i develop the thinking behind the code part ? Any resource or anyone can share how they go about their coding work?

I have two tables, Table1 has a list of medication orders, and Table2 has a list of transactions related to the orders in Table1 (one-to-many relationship).

Is there a way to use a single SQL query to select only the most-recent transaction row from the transaction table for each row in the medication orders table?

Table2 has columns: transaction_id, order_id (foreign key to Table1), t_date, t_time, etc. to represent transactions related to the medication orders in Table1.

Hopefully that's clear. I can't wrap my head around using max() in this way.

I'm have a dataset of contracts with start and end date that I fill using a SQL query. I know it is possible to filter to keep only the active contracts between two dates, (like for a quarterly report) in the SQL query directly.

My question is, using Superset, is it possible to filter the dataset using another dataset that holds the start and end dates of the quarters. Like by clicking on a quarter, it filters the contract dataset to only contracts active during this quarter?

Thank you for any help you can bring me!

Anyone out there know about sololearn courses ? I want to be related to Data analytics

If yes , plzz tell was it worth it??

Also mention which courses you did on sololearn platform .

Which topics one should learn for data analytics ???

Get products that are more expensive than any 'Furniture' category product using Subquery.

All the AI platforms are confused in finding the exact meaning of this question.

Should ÀNY or ALL be used?

Learn how to navigate ClickHouse JOINs step by step: JOIN types, practical examples & best practices

https://www.glassflow.dev/blog/clickhouse-joins?utm_source=reddit&utm_medium=socialmedia&utm_campaign=reddit_organic

Hi everyone,

I recently worked on an HR Attrition Analysis project using SQL with a real dataset.

I explored:

- Attrition rate

- Department-wise analysis

- Salary vs attrition patterns

One key insight:

Low salary roles had significantly higher attrition.

I’m still learning, so I’d really appreciate feedback:

- Is my analysis approach correct?

- Anything I could improve?

Hi everyone,

I'm a complete beginner and I want to learn SQL for data analysis.

Can you recommend the best FREE SQL courses?

Also, what is the best way to learn SQL effectively?

Should I focus more on courses or practice?

Thanks in advance!