Data Science Educational Resources
StrataScratch is a data science educational platform with over 1,000+ real interview questions from your favorite companies.
Interviews
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 -
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 -
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 -
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 -
What Is the Role of SQL Substring in Queries?
We explore the use of the SQL SUBSTRING() function to demonstrate its power in analyzing string formats, both for interview preparation and handling data.Shivani Arun -
Simplifying Python’s IF and AND Statements
Python IF and AND statements help you write clear, correct conditional logic by safely combining checks, handling edge cases, and keeping your code readable, efficient, and maintainable.Sara Nobrega -
Understanding FLOOR and CEILING Functions in SQL
We explore fundamental concepts of FLOOR and CEILING functions in SQL and demonstrate their value for interview preparation and handling data at scale.Shivani Arun -
How to Iterate Over a Dictionary in Python?
We explore fundamental concepts in Python ‘Iterate’ over a ‘Dictionary’ (dict) and learn iteration methods to search, update, modify, and transform data.Shivani Arun -