Chapter 10: Connecting to Databases Using JDBC

Many of the Web applications running on your server will process data, and most of that data will be stored in a database. The most popular databases, including MySQL, PostgreSQL, Oracle, SQL Server, Sybase, Interbase, and DB2, are based on relational concepts. You need to understand how Tomcat interacts with relational databases to better understand the requirements of your users.

In this chapter, you’ll see the many situations that will arise when configuring Tomcat to work with relational databases. More important, you’ll gain some hands-on experience configuring several examples. By the end of this chapter, you’ll be comfortable integrating databases with Tomcat.

Introducing SQL

The Structured Query Language (SQL) is a text-based query language that you use to perform operations with data stored in a relational database. These operations include selecting data for display, inserting data into the database, deleting data from the database, and manipulating database structure.

As an admin you won’t see much SQL in your Tomcat setup, because the server uses it behind the scenes to look up usernames and passwords. You will, however, have to be fairly familiar with simple SQL commands so that you can add and remove users from your Tomcat user databases. Because these are realm-related commands, they will be dealt with in Chapter 11.