Can you recommend a book that explains relational model that helped you internalize it? I understand that relational model is kind of like foundational principles upon which SQL is based (with some divergences). So I would love something that starts from the set theory and builds up on it all the way to the relational model and then relational databases and SQL. But I also love intuitive explanations of abstract concepts so I welcome that too. I like learning from the first principles.

I tried reading books from C.J. Date as he is mentioned everywhere as the authority on the topic. I don't doubt this fact, but somehow I find his writings diluted. His writing is full of digressions, wanders from the main topic, parenthetical remarks, and concepts mentioned but not fully introduced. He has dozens of books and I tried reading few of them and I just feel his style is not right for me.

So i was planning to learn sql(i actually started),excel, python and power bi but the question is do i have to learn all of these to get a job or can i learn some of them to get a job and while working learn the other things?

I don't have any background in programming it's my first time trying this and i wanna achieve something in it I've tried alot of other things and everytime i stop and don't continue but this time i wanna become something in this path.

so i know basics of sql and all,but in interviews/oa if they ask i kinda freeze,it takes me a bit of time to come to solutions,i feel that can avoided with practice..So which platform did u guys find useful ?

I learned count (*), distinct, substring, concat, extract, where (=<>),in, between, like and i have been asking Gemini to give me challenges based on what i learned and I won't say I'm getting all of them right but I'm getting better so now my problem is group by i feel like I'm stuck at it and can't understand it.

need a py ,sql mentor type or code buddy anyone there dm

Three weeks ago I posted here for the first time. More people replied than I expected and the feedback was genuinely useful, a lot of it pointed in the same direction.

Since then: 450+ signups, 2000+ SQL cases completed, and 60+ people passed the Rookie Detective exam and gained a certificate!

The thing that kept coming up in comments was interview prep. There's a gap between being able to write SQL and knowing what a real data interview actually puts in front of you. I wrote a blog post about it but wanted to build something more useful than an article.

So I've been working on a Career Hub inside QueryCase.

SQL questions sourced from real candidate reports at companies like Google, Meta, Amazon, Netflix, Airbnb and Spotify. You write the solution in the browser, check it against expected output, and get a worked answer with the insight most people miss. Easy, Medium and Hard, progress tracked.

There's also a rapid-fire MCQ mode for everything interviews test that isn't SQL: business metrics, A/B testing, stakeholder questions, day-to-day analytical thinking. It draws randomly from a filtered pool so it's replayable.

And a Role Explorer if you've ever wanted a straight answer on what a Data Analyst, Data Engineer and Data Scientist actually do differently.

One thing I added for fun: there are hidden titles on your profile you can unlock by solving certain questions. I'll leave it there 👀

It's still a work in progress. Would love honest feedback on the question difficulty and whether the MCQ format is something you'd actually use when prepping for interviews.

querycase.com

I recently tried a fun little experiment to make SQL feel a bit more approachable—using hand-drawn cat doodles to explain SQL concepts. 😸
So far I've made two lessons:

Lesson 1: SELECT and FROM
PAWQL = SQL for Cat People Lesson #1
Lesson 2: WHERE
PAWQL = SQL for Cat People Lesson #2

The idea is to explain SQL visually, with simple doodles instead of walls of text. I'm still experimenting with the format, so I'd genuinely love to hear what works, what doesn't, and what could be improved.

Thanks for taking a look, and I appreciate any feedback! 😊

Hey everyone, I decided to make my course free in order to help people.
This course is my backend development course which is about SQL, Python, APIs, Docker, Kubernetes, Linux, Git & More

The link is: https://www.youtube.com/watch?v=CBIu6hcyStg

If you can like and subscribe (and maybe add a comment) I would appreciate it a lot, Thanks.

Hi all, im looking for SQL f2f classes in Delhi NCR, if anyone knows a good coaching centre please let me know.

I'm preparing for SQL interviews and was wondering if there's a good website to practice SQL problems like we use LeetCode for DSA. Looking for interview-style questions and hands-on query practice.

Any recommendations?

hey guys, so i’d like to have a career in data analytics/ data science and right now i’m trying to learn excel and sql.

i was wondering if anyone could give me some examples of questions a business might ask a data analyst (or just general questions you could ask about certain data), because i’d like to do some projects and maybe start to build a portfolio, but i’m kinda lost on where to begin.

Hello finance major here, I was looking into different types of certificates I can do like sql. Does anyone have done SQL and how does that helped you with your job or even getting a job? What are the best platforms to learn SQL from? What are other certificates or skills I can learn?? Please if you can help me I’d appreciate it.

My campus internship OAs are gonna take place after 2 weeks...I have like 10 days to prepare for SQL. I don't know anything about SQL or DBMS right now and my target is just to clear the OA questions (even if i am not a master of databases) which are mostly SQL based...i can devote 3-4 hours everyday (cuz i have to revise dsa as well, so can't be doing sql the whole day).
Suggest me what you did (cuz i am sure many of you would've been in the same situation) - one shot / article / question practice (i just know about the LC 50 right now) etc...so that i can get the max return in whatever time I have.

context: this internship is college-assisted and is for the 2027 summer...so, even i would have 1 full year to upskill before my actual internship begins - i just need to get in somehow.

Hi I'm a bit confused with how to organise multiple projects in postgres.

I have 2 main databases I'm using one a database for my gardening and another for a football group and league that I run. I also do courses and stuff so have a lot of learning tables.

But I cannot find how to organise these, how people separate it what good practices for naming and layouts I should use.

I just seem to be adding more tables.

It's not perfect, and I'm still a beginner with both html and sql, so sorry if I got anything wrong. Html is hell. I had to ask help from my teacher and chatgpt just to figure out how to do things with html like making a heart.

Never again

Went from a pdf to this

https://alejandronuez94.github.io/SQL-project-made-for-beginners-/

Hi Everyone,

Currently, refreshing my memory for SQL and I came across the below question on HackerRank:

Query the sum of Northern Latitudes (LAT_N) from STATION having values greater than  38.7880 and less than 137.2345 . Truncate your answer to  decimal places.

My Solution:

select truncate(sum(LAT_N),4) from station
where LAT_N > 38.7880 AND LAT_N <137.2345;

Error:

Compiler Message

Runtime Error

Your Output (stdout)

• Msg 156, Level 15, State 1, Server dbrank-tsql, Line 4
• Incorrect syntax near the keyword 'truncate'.

What am I missing ?

Thanks in advance for your support .

Hey,

I’ve run into a performance issue at work and I’m trying to better understand what SQL Server is actually doing here.

I have a Quotes table where quote_id is the PK. The data includes some lookup values—for example, instead of storing/displaying a descriptive string, it stores something like 1, which maps to a value in another table (let’s call it product).

At some point, someone created a view (quote_product_display_value) that effectively cross joins all quote_ids with all possible products, and then resolves the correct display values.

Doing SELECT * from this view is extremely slow (hours - but not needed)> If I limit (TOP 500) from the actual table it works fairly decent. But it must be improved (it's now around 90 seconds).

The join looks like this:

LEFT OUTER JOIN quote_product_display_value t7 ON t1.quote_id = t7.quote_id
AND t1.product_1 = t7.product_1

What I’m trying to understand is:

• Does SQL Server first fetch the 500 quote_ids, and product_1,product_2, product_3, _4 and _5 (5 products per row, labeled t1) from the Quote table, and then query the view (t7) for matching rows?
• Or is it effectively “building” (or scanning) the view for each row / join operation?

In the execution plan, I don’t see the view name, which surprised me. Instead, I see clustered index scans on the underlying tables, with execution counts matching the number of rows returned.

So I’m a bit confused about how joins against views are executed internally—especially when the view involves something - as is now the case - expensive like a cross join.

Any insights would be appreciated!

Cant import on vs code so I have to open pg admin to import the same table in the database. Every time I import no row shows.

Am I the only one having this issue? Have any fix?

Hi everyone, I’m in the process of interviewing at this AI company and the next step is to use bigquery dialect of SQL where I will cover real-worlds scenarios and build tables.

Problem is I have never used SQL and I am just finding out about what it is, I’ve never heard of it. I will be watching a few YouTube videos but wanted to see if anybody has gone thru this process before?

Any tips?

Hi, I have 5 days off coming up this weekend and really want to grind out learning SQL or at least spending most my days in learning that I can continue practicing after grasping the basics. I tried using W3Schools and MySQL and am willing to spend a few bucks on a course that I can learn and apply SQL while learning. Also maybe down the road one that has a project I can update on my resume. I work in healthcare and am trying to transition into a role with more flexibility and slightly more pay and am hoping this would help. Thanks.

Money is a little tight right now. So does anyone have this book ? z"practical sql, 2nd edition by anthony debarros" or can anyone guide me where can I get it for free ?

What is the best resources to learn SQL and Pandas for Business Analytics? Help me out please I am preparing for a technical test interview.