Articles

GROUP BY

GROUP BY, HAVING, and WITH ROLLUP - A Colorful Guide to Learning SQL with Tables!

Learn how to use GROUP BY with aggregate functions, HAVING, and WITH ROLLUP to write more powerful and insightful SQL queries.

Normalization vs Denormalization

Normalization and Denormalization in SQL: Which One Should Be Used?

Normalization and denormalization are discussed as commonly asked topics in database design, frequently appearing in data engineer interviews and relevant to SQL performance

What is decision tree?

Understanding Decision Trees: A Beginner's Guide

Decision Tree is a simple and easy-to-understand machine learning method that makes predictions or classifications by splitting data through basic "yes/no" questions.

Confusion Matrix

Stop Trusting Accuracy! Other Ways to Evaluate Your Models

Accuracy alone is not enough; to truly evaluate a model's performance, metrics like precision, recall and F1 score are essential.