topic

23. Advanced: Window Functions

Idea: Window functions calculate values over a set of rows related to the current row.

Shape

SELECT Name, Price, AVG(Price) OVER (PARTITION BY Category) FROM Products;

Multiple Windows

ROW_NUMBER() OVER (ORDER BY Price DESC)

Placeholders for Examples

Coming soon: ranking products by price within category.

Advanced Deep Dive ADVANCED

Partitioning: PARTITION BY divides rows into groups for window calculations.

Ordering: ORDER BY within window functions controls calculation order.

Frame Specification: ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW defines window frame.

Performance: Window functions can be expensive; indexes on partition/order columns help.

Use Cases: Running totals, moving averages, ranking, percentiles.

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