Working with Databases

Abstract

Drupal depends on a database to function correctly. Inside Drupal, a lightweight database abstraction layer exists between your code and the database. In this chapter, you’ll learn about how the database abstraction layer works, how to use it, and even how to write your own driver. You’ll see how queries can be automatically modified by modules to restrict the scope of these queries. Then you’ll look at how to connect to additional databases (such as a legacy database). Finally, you’ll examine how to create, populate, and even delete tables when a module is installed, updated, or disabled, respectively.