November 2008
Intermediate to advanced
591 pages
17h 28m
English
Window functions are similar to aggregate functions in that they operate over many rows at one time. The difference lies in how you define those rows. Aggregate functions operate over the sets of rows defined by a query’s GROUP BY clause. With window functions, you specify the set of rows for each function call, so different invocations of a function within the same query can execute over different sets of rows.