In the last section of this chapter, I will discuss the following:
- Using the GROUPING SETS in T-SQL
- Using the
rx_data_step()function from therevoscalepyPython package - Introducing the
dplyrpackage in R
In Chapter 1, Writing Queries with T-SQL, I discussed the core T-SQL SELECT statement clauses, and showed how you can group and aggregate data. But SQL Server has more hidden gems. Maybe you need to create many different groupings and aggregates. In T-SQL, you can help yourself with the GROUPING SETS clause.
You could create aggregates over multiple different grouping variables by using multiple SELECT statements with a single GROUP BY clause for separate grouping, and then you could use the UNION clause to return all separate result sets as a single unioned result set. However, you can achieve the same result in a single query with the GROUPING SETS clause. You can define multiple sets of variables for grouping, and multiple...