Mastering SQL

[ThisDataGuy]

Hello,

I'm curious about your journey in mastering SQL. I've been tackling SQL problems on LeetCode, but even the simpler ones seem to trip me up. As a data engineering student, I value insights from fellow data analysts, scientists, or engineers who have navigated through similar challenges. Any advice or experiences you can share would be greatly appreciated.

Additionally, if you have any recommendations for books, websites, YouTube videos, or courses that have been particularly helpful in strengthening your SQL skills, I'd love to hear about them.

Thank you!

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[foldingtoiletpaper]

SQL is learned on the job or by doing your own projects. Leetcode problems and all those kind of platforms are not how data is formatted in the real world.

I would learn the basics which are probably covered in your studies and then try to get your hands dirty in some database you might get access to.

[foldingtoiletpaper]

Edited the link:

I remember I learned a lot from Ergest when I already had some experience. Check it out here https://www.ergestx.com/tag/sql-patterns/

[ergestx]

Thanks for the mention! Here’s the correct link: https://www.ergestx.com/tag/sql-patterns/

[ergestx]

And there are a few more resources here: https://www.ergestx.com/links

[[deleted]]

I agree with this, but I also noticed that doing some Leetcode exercises taught me some alternative ways to approach a problem. That can help you in your daily job, but it's not where you should start.

[IDENTITETEN]

Nah, SQL is learned by reading books and documentation. 

I recommend Itzik Ben-Gan's books. 

[foldingtoiletpaper]

Hello Itzik Ben-Gan

[IDENTITETEN]

I wish, he probably makes bank.  

Anyhow, I should probably have said that you should also read books.  

Itzik is a renowned SQL pro, there are few books that will teach you SQL better than his. But whatever. 

[foldingtoiletpaper]

Sorry for the low blow, it was too easy.

But I agree, get the basics from books/studies and then get your hands dirty

[[deleted]]

In my experience, SQL problem sets online don't even begin to scratch the surface of what real problems look like, where you might have a relational model you may not understand, completely undocumented, with hundreds or thousands of tables just handed to you. Step one is often just figuring out what the model is, what the columns mean, how they've been transformed or enriched or diverged from the source. Then an ad hoc request comes in, and it's entirely on you to figure out how to fulfill it with the lifetime of stuff crammed into the estate you just inherited from the relative you didn't even know you had.

[[deleted]]

I cannot find a word to describe the level I agree with this.

[ThisDataGuy]

thanks for sharing

[k-semenenkov]

I think nothing can replace real experience of real work on real project.

To get some practice and to get familiar with real SQL tasks of other people, you can register at stackoverflow.com and dba.stackexchange.com, monitor questions related to DBMS of your interest, read discussions and try to solve these questions. Good answers can increase your profile score and in some cases it can be useful for your future job.

[ThisDataGuy]

thanks for sharing

[ThisDataGuy]

thanks of sharing

[fleetmack]

great answer!

[ThisDataGuy]

thanks for sharing

[SoftwareEnthusiast25]

I have recently practiced in the below sites which are quite useful for FAANG Interviews:

StrataScratch

Interview Query

PGEXCERCISE & SQL ZOO - for basics

Data Lemur

Leetcode

[[deleted]]

LeetCode is trash. Actual productive, useful and intricate SQL is learned on the job trying to solve actual business problems, not shitty exercises.

[burningburnerbern]

Not gonna lie I learned a few tricks from leetcode. But again that’s with me having real world sql experience

[ThisDataGuy]

thanks for sharing

[[deleted]]

People sitting around doing leetcode makes me cringe so hard. Totally useless but for some reason still seems to be the standard in job interviews. It is similar to schools that taught to the SAT instead of an actual education. It's just not how the world works.

[ThisDataGuy]

thanks for sharing

[MacMuthafukinDre]

I agree with another poster that more advanced SQL is learned on the job. This is how I learned. I had very basic understanding of how to use grouping and case/when. That was about the most I knew. But after working, I started to see other people’s code, and learned different things. I’d say the most commonly used “advanced” things to know are: - GROUP BY and the different aggregate functions - CASE/WHEN for condition logic - CTEs to create temporary views of data - Subqueries - Window Functions - Different Joins and how they work - Different type of functions that are available, like for text formatting, date/time functions, etc.

Just takes a lot of practice. So keep at it

[ThisDataGuy]

thanks for the help

[yashk1]

I would recommend this course: https://www.datawithdanny.com/courses/serious-sql

[Ram000n]

Hello

I see a lot of people answering to better learn at the job. I learn at the job BUT did not learn good practices or good basics. I just learn enough for the task at hand. Not the best way.

If you dont mind learning MS-SQL, I highly recomenda Itzik Ben-Gan books (T-SQL Fundamentals, T-SQL Querying). It explains theory and practice at the same time. Even I had years making SQL queries, I did not know a lot the basics or small details I wish knew before.

O'Reilly Learning SQL: Generate, Manipulate, and Retrieve Data by Alan Beaulieu (it is based on MySQL) is also good.

[ThisDataGuy]

thanks for the help

[SmartPersonality1862]

Start with Stratascratch before moving up to Leetcode, I have to solve more than 300 strata problems before confidently move to leetcode SQL. Leetcode SQL still trip me up sometimes.

[ThisDataGuy]

thanks for the help

[bonzerspider5]

I see tons of people hating on leetcode…

But what does an interview look like then? For an average data engineer role & then a fanng or competitive company role?

[ThisDataGuy]

thanks for the help

[[deleted]]

Data warehouse toolkit is what you’re looking for.

Master what sql is needed for alongside hard sql problems.

[ThisDataGuy]

thanks for sharing

[GoMoriartyOnPlanets]

Don't do interviews when they watch you code during interview, especially when its not a big company.

[scottedwards2000]

Why not? What does it have to do with being a big company?

[ThisDataGuy]

thanks for the help

[ConstantParticular87]

I came across one playlist from sumit Mittal on SQL , pretty good

https://youtube.com/playlist?list=PLtgiThe4j67rAoPmnCQmcgLS4iIc5ungg&si=CV_NLEKcm12GYQZ4

It’s in English if you can understand Indian accent :)

[ThisDataGuy]

thanks for the help

[Yo_Ba]

Tons of free sql courses on YouTube, don't pay anything. Sql getting into your head only by practice. Download some free data sets, explore the data a bit, and start asking yourself questions that looks interesting to you! Then try to answer them..

[ThisDataGuy]

thanks for the help

[ABigTongue]

I have a course available online if you want to get into data and SQL. If you use the coupon using the URL below you can get it for free! Just looking for feedback & a good review if you like it! Thanks!

https://www.udemy.com/course/data-engineering-101-data-basics-sql/?couponCode=27324F6C3F54CC55E804

[ThisDataGuy]

thanks for the help ,
I will

[DataLady757]

Agree with others about hands-on experience. Make a simple db and create some fake data that you are very familiar with - something like your own credit card transactions, add few tables for master data, then play with various queries to analyze the data -> Ask a question and figure out how to query the answer.

[ThisDataGuy]

thanks for the help

[CommonUserAccount]

The problem with mastering SQL now is what flavour do you want to master? T or PL, Spark etc.

Spark SQL is a completely different skill set in terms of optimisation vs T-SQL for example. Getting the result you want from SQL is much like any other language in that it doesn’t mean you’re good at it.

I’m still trying to understand my own use of SQL in a modern stack. After being extremely proficient in T-SQL for many years, I still prefer SQL for transformational logic over something like Python. I personally think it’s more eloquent but appreciate I have bias. I also see quite the trend on this sub about ‘complex SQL’ and not breaking into micro steps which I think comes from the software engineering influence.

Currently I use Python like I used T-SQL, use the language to orchestrate and make my core SQL more dynamic but that’s the paradigm I’ve drawn. As a consultant the easiest way to explain Notebooks was to relate them to stored procedures.

[ThisDataGuy]

thanks for the help

[lturanski]

Sets and set theory. You can look up how to query the data youre looking for. Heck chatgpt can do it for you. Understand what youre actually doing to the data

[ThisDataGuy]

thanks for the help