Window Functions (SQL)
💡 Quick Definition: SQL functions that perform calculations across a set of table rows related to the current row without collapsing rows like GROUP BY.
Detailed Explanation & Workplace Application
Window functions like ROW_NUMBER(), DENSE_RANK(), LEAD(), and LAG() with OVER(PARTITION BY ... ORDER BY ...) enable running totals, moving averages, and rankings in a single query.
Practical Syntax / Framework Formula
SELECT employee_name, department, salary,
AVG(salary) OVER(PARTITION BY department) as dept_avg_salary,
salary - AVG(salary) OVER(PARTITION BY department) as salary_diff
FROM Employees;