Chapter 8. Relational Databases


  • Relational database concepts

  • The MySQL database server

An application can have the most beautiful design or slick intuitive interface, but the fact remains that without the ability to retrieve, update, and store useful data, that application won't see much use. Most data-driven Web applications have a relational database on the back end to manage that data. In this chapter, you learn about key relational database concepts and work with MySQL, a popular open-source database server that powers many of today's Web applications.

Relational Database Concepts

The purpose of a relational database is to store data and allow for the retrieval and manipulation of stored data in response to a user's query. Data in a relational database is stored in structures called tables. Data is retrieved from the tables in a relational database by using a querying language called SQL. SQL can also be used to manipulate data stored in database tables. Complex data manipulation and retrieval operations can be grouped together in a stored procedure, which is a construct much like a Java method or ActionScript function. Let's look at these three relational database concepts in more detail.


Tables in a relational database are structured much like spreadsheets, composed of columns and rows. Columns describe each field of data being stored, and rows each contain a single unit of stored data.

Typically, a row in a database table represents a single entity. For example, ...

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