Chapter 17
Databases

In earlier chapters, we used files to store data. This is fine for small problems, but as our data sets become larger and more complex, we need something that will let us search for data in many different ways, control who can view and modify the data, and ensure that the data is correctly formatted. In short, we need a database.

Many different kinds of databases exist. Some are like a dictionary that automatically saves itself on disk, whereas others store backup copies of the objects in a program. The most popular by far, however, are relational databases, which are at the heart of most large commercial and scientific software systems. In this chapter, you will learn about the key concepts behind relational databases and how to perform a few common operations.