SQL Server provides the GROUP BY clause as a means to take a set of detailed values and summarize them into aggregated values. The detailed records can be aggregated based on one column, as well as expressions, which are specified in the GROUP BY clause. This article explores how to return summarized data using the GROUP BY and HAVING clauses.
Test data
In order to demonstrate how to use the GROUP BY and HAVING clauses, some test data will be needed. All of the examples in this article will use a table called Invoice that is created in tempdb, using