Chapter 16
Databases
WHAT YOU WILL LEARN IN THIS CHAPTER:
- Understanding Perl’s DBI module
- Connecting to databases
- Selecting data from databases
- Using binding parameters
- Changing your data
- Using transactions
WROX.COM CODE DOWNLOAD FOR THIS CHAPTER
The wrox.com code downloads for this chapter are found at http://www.wrox.com/remtitle.cgi?isbn=1118013847 on the Download Code tab. The code for this chapter is divided into the following major examples:
- example_16_1_fetch.pl
- lib/MyDatabase.pm
- listing_16_1_make_database.pl
- listing_16_2_populate_database.pl
- listing_16_3_select.pl
A database is a place to store your data. It can be a regular file, a sheet of paper, or a hierarchical database such as IMS (no longer widely used). Today, when most people say “database,” they’re referring to what most people call relational databases. If you have a background in programming, you’ve probably heard of several of them, such as MySQL, PostgreSQL, Oracle, Sybase, and many others. Each of these offers a variety of different features, some favoring data integrity, others focused on performance, and some striving for both.
In this chapter you acquire a minimum knowledge of using databases in Perl. You will use the SQLite database and Perl’s DBI module. I chose SQLite because it’s easy to install and Perl’s DBI module because it is the standard for connecting to databases. There are other tools, such as object-relational mappers (ORMs) that try to hide some of the complexity of databases, but under ...
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