Data Science Educational Resources
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SQL Articles, Tutorials & Interview Questions
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 -
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 -
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 -
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 Create Pivots in SQL (with examples)
Reshaping data using Pivots is table-stakes in data science. Learn about its importance, techniques, and implementation.Shivani Arun -
A Comprehensive Step-by-Step Guide to Full Outer Join in SQL
The FULL OUTER JOIN is a very useful but often overlooked SQL join. In this article, we’ll discuss how it works, when to use it, and give practical examples.
Nathan Rosidi -