So far, we have worked with MySQL, and you already have a good idea of what you can do with it. However, connecting to the client and performing queries manually is not our goal. What we want to achieve is that our application can take advantage of the database in an automatic way. In order to do this, we will use a set of classes that comes with PHP and allows you to connect to the database and perform queries from the code.
PHP Data Objects (PDO) is the class that connects to the database and allows you to interact with it. This is the popular way to work with databases for PHP developers, even though there are other ways that we will not discuss here. PDO allows you to work with different database systems, so you are not tied to MySQL only. In the following sections, we will consider how to connect to a database, insert data, and retrieve it using this class.