SQL • LESSON 27

PARTITION BY

Learn how to divide query results into groups while applying window functions independently to each group.

🔴 Advanced⏱ 3 Minutes⭐ 460 XP

🤔 THE QUESTION

How can we rank employees separately within each department?

💡 WHAT IS IT?

PARTITION BY divides the rows into groups before the window function performs its calculation.

🎯 WHAT IS IT USED FOR?

It is useful when you need rankings, totals, averages, or other calculations separately for each category, department, customer, or group.

💻 EXAMPLE

SELECT name,
department,
salary,
RANK() OVER (
  PARTITION BY department
  ORDER BY salary DESC
) AS department_rank
FROM employees;

Practice using PARTITION BY to rank employees separately within each department.