Beginning SQL Queries: From Novice to Professional, Second Edition

© Clare Churcher 2016

Clare Churcher, Beginning SQL Queries, 10.1007/978-1-4842-1955-3_9

9. Window Functions

Clare Churcher¹ 

(1)Studio B Productions, Great Neck, New York, USA

Window functions were added to standard SQL in 2003 and provide considerable extra capability for dealing with aggregation. Window functions allow us to perform aggregates on a “window” of data based upon the current row. This provides an elegant way to specify queries to perform actions such as ranking, running totals, and rolling averages. Window functions also provide considerable flexibility when it comes to grouping data for aggregation as they allow a single query to have several different groups or partitions. It is also possible to reference the data contributing to ...