One of the most confusing concepts in data modeling is understanding the difference between ProductKey and ProductAlternateKey. Simple Explanation: ProductKey […]
This SQL practice note uses a simple healthcare example with two tables: Patients and Diagnoses. The goal is to review
What business question is this SQL pattern trying to answer? As I continue learning SQL, I am starting to see
Business Question (AdventureWorks): Find all products in the Bikes category that have a list price higher than the average list
Understanding when to use EXISTS and when to use JOIN is very important in SQL. 1. Use EXISTS when you
While both JOINs and subqueries can solve the same problem, database engines (like SQL Server) generally perform much better with
Window Functions perform calculations across a set of rows related to the current row — without collapsing the result set
Joins combine data from two or more tables based on related columns. Understanding advanced join types and techniques is crucial
The GROUP BY clause groups rows with the same values in specified columns into summary rows. The HAVING clause filters
A Common Table Expression (CTE) is a temporary result set that you can reference within a SELECT, INSERT, UPDATE, or