In this chapter, we have learned how to query an SQL database efficiently using Modern SQL. We have defined what Modern SQL is and how we can use it. We have acquired knowledge of how to convert certain traditional SQL queries into modern ones and when it is best to do so. Moreover, by doing so, we now better understand how Modern SQL can help us optimize a server's performance in more than one way.

In the next chapter, we will cover a few of JavaScript’s best and worst parts, especially those that pertain to code efficiency and overall performance, and how a developer should always write safe, reliable and highly efficient JavaScript code, mostly by avoiding danger-driven development.