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520. JOIN with Window Functions

Learn how JOINs can be combined with window functions to perform advanced analytical calculations.

📘 Lesson 520 of 728 ⏱ 15 min 🎯 Advanced

Window functions calculate values across related rows without collapsing them into a single row per group. When combined with JOINs, they can provide analytical calculations across data from multiple tables.

This combination is powerful for ranking, running totals, comparisons, and advanced business analysis.

Join customers with orders and rank each customer's orders by amount.

SQL 
SELECT
    c.CustomerName,
    o.OrderID,
    o.OrderAmount,
    RANK() OVER (
        PARTITION BY o.CustomerID
        ORDER BY o.OrderAmount DESC
    ) AS OrderRank
FROM Customers c
INNER JOIN Orders o
    ON c.CustomerID = o.CustomerID;

Used in sales ranking, financial analysis, customer analytics, performance reporting, and advanced dashboards.

  • JOIN combines related information.
  • Window functions analyze rows without collapsing them.
  • PARTITION BY defines the analytical group.
  • ORDER BY inside the window defines calculation order.
  • This pattern is useful for advanced analytics.
Can window functions be used with JOINs?

Yes. A query can JOIN related tables and then apply window functions to the resulting rows.

Why combine JOIN and window functions?

It allows related information from multiple tables to be combined with advanced row-level analytical calculations.

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