How would you partition by department to get the highest paid employee in each department?

To retrieve the highest paid employee in each department, you can use a window function with ROW_NUMBER() to rank employees within each department by salary in descending order, then filter for rank = 1. For example: SELECT dept, employee, salary FROM (SELECT dept, employee, salary, ROW_NUMBER() OVER (PARTITION BY dept ORDER BY salary DESC) AS rn FROM employees) t WHERE rn = 1; This returns one row per department, the employee with the highest salary. If you need the top N employees per department, replace rn = 1 with rn <= N. An alternative is to use a correlated subquery: SELECT e.* FROM employees e WHERE e.salary = (SELECT MAX(salary) FROM employees WHERE dept = e.dept); However, the window function approach is often more efficient, especially on large tables, because it can leverage indexes on the partition and order columns. It also handles ties gracefully if you use RANK() or DENSE_RANK() instead of ROW_NUMBER().