Perl in a Nutshell

Chapter 12. Databases and Perl

Since one of Perl’s greatest strengths is working with text, a genuine concern is how to store data. Flat files are one possibility, but don’t scale very well, to say the least. Instead, you’ll need to use a database.

There are two general solutions to using databases with Perl. For simple database purposes, DBM (Database Management) will serve your needs. DBM is a library supported by many (if not all) Unix systems and many non-Unix systems as well. If you use DBM with Perl, you can manipulate databases just like any hash.

For more elaborate databases with SQL interfaces, you can get a complete database product or shareware equivalent (depending on your needs) and use DBI and DBD. DBI is a module that provides a consistent interface for database solutions. A DBD is a database-specific driver that translates DBI calls as needed for that database.

In this chapter, we’ll quickly cover DBM and then talk more at length about DBI/DBD.

DBM Databases and DBM Hashes

DBM is a simple database management facility for Unix systems. It allows programs to store a collection of key-value pairs in binary form, thus providing rudimentary database support for Perl. Practically all Unix systems support DBM, and for those that don’t, you can get Berkeley DB from http://www.sleepycat.com/db.

To use DBM databases in Perl, you can associate a hash with a DBM database through a process similar to opening a file. This hash (called a DBM array) is then used to access and modify ...