SQL Window Functions

Window functions let you run calculations across a set of rows related to the current row.

ROW_NUMBER Example

SELECT id, name, ROW_NUMBER() OVER (ORDER BY salary DESC) AS row_num
FROM employees;

Assigns a unique row number based on salary.

RANK Example

SELECT id, name, RANK() OVER (ORDER BY salary DESC) AS rank
FROM employees;

Gives the same rank for ties.

Key Difference

• ROW_NUMBER → No duplicates
• RANK → Handles ties by skipping numbers

Tip: Use DENSE_RANK if you don’t want gaps in ranking.