Uploaded January 2021 | Updated September 2026, 17 hours ago

---

We’re going to go over the most common data science interview question for 2021 in this video. Really it’s 3 of the most common concepts tested on all coding interviews wrapped in one question. I see this question (or version of this question) on almost every interview I’ve been on or given. Follow along with me and see if you would be able to answer this question.

Link to the question: platform.stratascratch.com/coding/10300-premium-vs-freemium?python=&utm_source=youtube&utm_medium=click&utm_campaign=YT+description+link

This question is from Microsoft but versions of this has been found at other tech companies like Facebook, Google, Airbnb, Doordash, and others. The 3 concepts tested are SQL JOINs, CASE statements, and subqueries / common table expressions (SQL CTEs).

______________________________________________________________________

👉 Subscribe to my channel: bit.ly/2GsFxmA
👉 Playlist for more data science interview questions and answers: bit.ly/3jifw81
👉 Practice more real data science interview questions: platform.stratascratch.com/coding?utm_source=youtube&utm_medium=click&utm_campaign=YT+description+link

______________________________________________________________________
Timestamps:

Intro: (0:00)
3 common technical concepts: (0:47)
Interview question: (1:20)
1st concept - Advanced JOINs: (1:42)
2nd concept - CASE statements: (4:52)
3rd concept - Subquery / CTE:: (7:46)
Conclusion: (10:41)

______________________________________________________________________
About The Platform:

I'm using StrataScratch, a platform that allows you to practice real data science interview questions. There are over 1000+ interview questions that cover coding (SQL and python), statistics, probability, product sense, and business cases.

I created this platform because I wanted to build a resource to specifically help prepare data scientists for their technical interviews and to generally improve their analytical skills. Over my career as a data scientist, I never was able to find a dedicated platform for data science interview prep. LeetCode and HackerRank were the closest but these platforms specifically serve the computer developer community so their questions focus more on algorithms that working with data.

So, if you want more interview practice with real data science interview questions, visit platform.stratascratch.com/coding?utm_source=youtube&utm_medium=click&utm_campaign=YT+description+link. All questions are free and you can even execute SQL and python code in the IDE, but if you want to check out the solutions from me or from other users, you can use ss15 for a 15% discount on the premium plans.

______________________________________________________________________
Contact:

If you have any questions, comments, or feedback, please leave them here!
Feel free to also email me at nathan@stratascratch.com
______________________________________________________________________