EasyWindow Functions

ROW_NUMBER: number each row within a group

The query

SQL

SELECT
  first_name,
  last_name,
  dept_id,
  salary,
  ROW_NUMBER() OVER (PARTITION BY dept_id ORDER BY salary DESC) AS row_num
FROM employees
ORDER BY dept_id, row_num;

Tested against PostgreSQL 16

Note

“ROW_NUMBER assigns unique sequential integers. PARTITION BY creates groups (like GROUP BY without collapsing rows).

Tables referenced

employees10 cols