Window Functions in SQL

From the SQL cheat sheet · Window Functions · verified Jul 2026

Window Functions

ROW_NUMBER, RANK, LAG, LEAD, running totals, and partitioned aggregates.

sql

-- ROW_NUMBER
SELECT name, salary,
  ROW_NUMBER() OVER (ORDER BY salary DESC) AS rank
FROM employees;

-- RANK with PARTITION BY
SELECT name, department, salary,
  RANK() OVER (PARTITION BY department ORDER BY salary DESC) AS dept_rank
FROM employees;

-- Running total
SELECT date, amount,
  SUM(amount) OVER (ORDER BY date) AS running_total
FROM payments;

💡 Window functions compute across rows without collapsing them — unlike GROUP BY

⚡ ROW_NUMBER + CTE is the standard pattern for "top N per group" queries

📌 RANK has gaps after ties (1,2,2,4); DENSE_RANK has no gaps (1,2,2,3)

🟢 LAG/LEAD let you compare each row to its previous/next row — great for trend analysis

windowrow-numberranklaglead

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