Practical SQL

12ADVANCED QUERY TECHNIQUES

Sometimes data analysis requires advanced SQL techniques that go beyond a table join or basic SELECT query. For example, to find the story in your data, you might need to write a query that uses the results of other queries as inputs. Or you might need to reclassify numerical values into categories before counting them. Like other programming languages, SQL provides a collection of functions and options essential for solving more complex problems, and that is what we’ll explore in this chapter.

For the exercises, I’ll introduce a data set of temperatures recorded in select U.S. cities and we’ll revisit data sets you’ve ...