Programming the Perl DBI

Data Source Names

When connecting to a database via the DBI, you need to tell the DBI where to find the database to connect to. For example, the database driver might require a database name, or a physical machine name upon which the database resides. This information is termed a data source name, and of all the aspects of DBI, this is possibly the most difficult to standardize due to the sheer number and diversity of connection syntaxes.

The DBI requires the data source name to start with the characters dbi:, much like a URL begins with http:, and then the name of the driver, followed by another colon—for example, dbi:Oracle:. Any text that follows is passed to the driver’s own connect() method to interpret as it sees fit. Most drivers expect either a simple database name or, more often, a set of one or more name/value pairs separated with semicolons. Some common examples are listed later in this section.

For example, mSQL requires the hostname, database name, and potentially, the TCP/IP port number for connecting to the database server. However, Oracle may require only a single word that is an alias to a more complicated connection identifier that is stored in separate Oracle configuration files.

DBI offers two useful methods for querying which data sources are available to you for each driver you have installed on your system.

Firstly, you can get a list of all the available drivers installed on your machine by using the DBI->available_drivers() method. This returns a list ...