Chapter 5: Aggregations and Grouping
Jason Brimhall, Jonathan Gennick, Wayne Sheffield · Apress eBooks · 2015
Aggregate functions are used to perform a calculation on one or more values, and the result is a single value. If your query has any columns with nonwindowed aggregate functions, then a GROUP BY clause is required for the query. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.