Data Science Educational Resources
StrataScratch is a data science educational platform with over 1,000+ real interview questions from your favorite companies.
Guides
Using SQL Regex to Classify and Filter Messy Data
Messy ratings, jumbled addresses, and buried keywords: SQL regex filters and classifies all of it inside the query, in seven real interview questions.
Sara Nobrega -
How SQL EXISTS Works and When to Use It
Ignore EXISTS at your own peril! Learn how SQL EXISTS actually works, how it compares to IN and JOIN, and solve actual interview questions.
Tihomir Babic -
SQL Execution Order Explained With Real Query Examples
SQL execution order decides how queries actually run. Learn why FROM comes first, how aliases fail in WHERE, and when to use HAVING, with real examples.Sara Nobrega -
You’re Not Unemployed. You’re Unemployable. (Here’s Why.)
Five reasons your data science job search isn't working, and what to fix before sending another application.Tihomir Babic -
Understanding NULL Semantics in SQL
NULL in SQL is often a source of confusion, leading to bug propagation. Learning how NULL behaves in different scenarios to keep your query outputs trustworthy.Tihomir Babic -
INTERSECT vs UNION in SQL for Reasoning About Overlapping Data
INTERSECT vs UNION in SQL: choose the wrong set operator, and the query returns a plausible but incorrect result, with no error and no warning to tell you so.Sara Nobrega -
The AI Ponzi Scheme: Slap on a Chatbot, Raise Millions, Leave Engineers Holding the Bag
Everyone's chasing AI riches, but when the bubble bursts, engineers, not investors, will be left cleaning up the mess.Tihomir Babic -
Python List Length: How to Find the Size of a List in Python
One-stop shop for product data scientists to brush up on the size of the list in Python - a core fundamental that’s an element of many key interview patterns.
Shivani Arun -
How To Pass Data Interviews for Machine Learning Engineer Roles
How do you get a machine learning engineer job? By passing the interviews, obviously. In this article, we deal with exactly that by detailing how to prepare.Tihomir Babic -
You Don’t Need to Be a Math Genius for Data Science
Learn the truth about data science interviews and how deep you actually need to go into maths.Tihomir Babic -
How to Use SELECT INTO in SQL for Analytics
SELECT INTO is an often-overlooked tool for analytics. Here we explain its syntax, use cases, how to use it in staging, and how it is tested in interviews.Tihomir Babic -
Retention in SQL: How to Calculate User and Cohort Retention?
One-stop shop for product data scientists and job candidates: what is retention and its different types, how to calculate them, with the SQL application.Shivani Arun -