Window functions (MySQL 8.0+)

Last reviewed May 28, 2026 Content v20260528

Track mode

sql_sandbox

Means

SQL sandbox

Reading

~1 min

Level

advanced

This lesson

This lesson teaches Window functions (MySQL 8.0+): the SQL patterns, schema habits, and query reasoning you need before advancing in MySQL.

Teams query Window functions (MySQL 8.0+) on every MySQL codebase—skipping it leaves gaps in debugging and data reviews.

You will apply Window functions (MySQL 8.0+) in contexts like: Web apps on shared hosting, ecommerce, and many startups’ first production DB.

Copy MySQL SQL into the mysql client, local MySQL/MariaDB, or DB Fiddle (MySQL dialect)—use DESCRIBE and EXPLAIN where lessons show them. The in-browser lab ships later; mysql client is the practice path now.

When InnoDB, indexes, and EXPLAIN from intermediate lessons make sense in the mysql client.

ROW_NUMBER, RANK, and SUM OVER () arrived in MySQL 8—verify VERSION() before using in production mixed fleets.

Ranking

SELECT id, customer_id, total,
  ROW_NUMBER() OVER (PARTITION BY customer_id ORDER BY total DESC) AS rn
FROM orders;

Practice: Run on practice.

Running total

SELECT id, total,
  SUM(total) OVER (ORDER BY created_at) AS running
FROM orders;

Important interview questions and answers

Q: PARTITION BY?
A: Resets window per group—like GROUP BY but keeps detail rows.
Q: MariaDB version?
A: MariaDB 10.2+ supports window functions—check docs for syntax edge cases.

Self-check

Rank orders per customer by total.
MySQL version for window functions?

Tip: Confirm VERSION() >= 8 before window functions in prod.

Interview prep

MySQL version?: 8.0+ for window functions.
PARTITION BY?: Defines per-group window.

Discussion

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Starter discussion topics

MySQL 8 needed?
PARTITION BY?

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