MySQL supports window functions that, for each row from a query, perform a calculation using rows related to that row. The following sections discuss how to use window functions, including descriptions of the OVER and WINDOW clauses. The first section provides descriptions of the nonaggregate window functions. For descriptions of the aggregate window functions, see Section 12.20.1, “Aggregate (GROUP BY) Function Descriptions”.

For information about optimization and window functions, see Section 8.2.1.20, “Window Function Optimization”.