Summary

In this chapter, we learned the basics of databases and SQL, which are topics that many data scientists encounter in interviews. In fact, as a data scientist, you will almost certainly be quizzed on this topic during interviews. We touched on basic querying concepts, subqueries, joins, window functions, evaluation order, aggregation, filtration, and how to approach complex problems. However, SQL is yet another topic that commands an entire book on its own.

Rest assured that in most cases, there is more than one way to solve a problem, but there are often limited optimal ways to do so. Thus, be sure to spend adequate time practicing the concepts discussed in this chapter. Try not to memorize queries; instead, familiarize yourself with the common use cases explained in this chapter. Follow the aforementioned steps to break down complex problems, but be aware that the order of these steps is not set in stone. Once mastered, you will be able to identify the right query for any...