Theory: Yes, We Need It!

In order to write performant queries, database developers need to understand how queries are processed by the database engine. And to do that, we need to know the basics of relational theory. If the word “theory” sounds too dry, we can call it “the secret life of a database query.” In this chapter, we will take a look at this “secret life,” explaining what happens to a database query between the moment you click “Execute” or press Enter and the moment you see the result set returned from the database.