Answer
A ranking query uses a window ranking function over a defined ordering. • ROW_NUMBER gives unique sequence numbers. • RANK leaves gaps after ties, while DENSE_RANK does not. • PARTITION BY creates separate rankings for groups.
💡 SQL Example
SELECT name, department_id, DENSE_RANK() OVER (PARTITION BY department_id ORDER BY salary DESC) AS salary_rank FROM employees;
Result
A salary rank inside each department
⚡ Quick Revision
Choose ROW_NUMBER, RANK, or DENSE_RANK according to tie behavior.