Programming PHP

The protocol is the communication protocol to use. The two common values are
"tcp" and "unix", corresponding to Internet and Unix domain sockets. Not every
database backend supports every communications protocol.
These are some sample valid data source names:
mysql:///webdb
mysql://localhost/webdb
mysql://bondview@localhost/webdb
mysql://bondview@tcp+localhost/webdb
mysql://bondview:007@localhost/webdb
In Example 8-1, we connected to the MySQL database webdb with the username
bondview and password 007.
A common development technique is to store the DSN in a PHP file and include that
file in every page that requires database connectivity. Doing this means that if the
information changes, you don’t have to change every page. In a more sophisticated
settings file, you might even switch DSNs based on whether the application is running
in development or deployment mode.
Connecting
Once you have a DSN, create a connection to the database using the connect( )
method. This returns a database object you’ll use for tasks such as issuing queries
and quoting parameters:
$db = DB::connect(DSN [, options ]);
The options value can either be Boolean, indicating whether or not the connection is to
be persistent, or an array of options settings. The options values are given in Table 8-2.
Table 8-2. Connection options
Option Controls
persistent Connection persists between accesses
optimize What to optimize for
debug Display debugging information
By default, the connection is not persistent and no debugging information is displayed.
Permitted values for optimize are 'performance' and 'portability'. The
default is 'performance'. Here’s how to enable debugging and optimize for portability:
$db = DB::connect($dsn, array('debug' => 1, 'optimize' => 'portability'));
Error Checking
PEAR DB methods return DB_ERROR if an error occurs. You can check for this with
DB::isError( ):
194 | Chapter 8: Databases
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