Filtering Data in SQL

One of the first essential skills in SQL is filtering data with the WHERE clause. It’s how you narrow your results to exactly what you need.

Example:

SELECT *  
FROM Patients  
WHERE Age > 65;

This query shows only patients older than 65.

In the future, I could use this approach to quickly find all geriatric patients on a high-risk medication to support a medication review.

💡 Future clinical idea: Create a query to identify patients on medications requiring renal dose adjustments, filtered by their latest eGFR values.