PHP provides the adept developer with the tools to create some powerful Web solutions. Moreover, with the ability to add additional functionality through extensions, it makes creating solutions easy.

The PHP Extension and Application Repository (PEAR) is a framework that helps developers create solutions through high-level APIs or packages. The PEAR is also a distribution system in that it provides a means for automatic installation of these packages. This week, I'll highlight what I believe is one of the more important packages: the DB package.

The DB package is an object-oriented style abstraction layer to PHP's underlying database connectivity and querying; it's compatible with both PHP 4 and 5. The DB package currently supports the following extensions: dbase, fbsql, interbase, informix, msql, mssql, mysql, mysqli, oci8, odbc, pgsql, sqlite, and Sybase.

If you've used the mysql_* functions to attach to and query MySQL databases, you're probably familiar with the different resultsets available. The most common two resultsets come as either an array with each field being an indexed element or as an associative array with each field being a key/value pair. PEAR DB provides these two resultsets, as well as an object type, which creates a dynamic object where each field is a property of the object. The associative array and the object type are probably going to be the most familiar to developers coming from ADO connectivity on Windows machines.

In ADO, a resultset (or a Recordset) is returned as a navigable collection of rows. Each row is a collection of Field objects. Each Field object has a Name and a Value property (i.e., the name of the field and the data contained within that field, respectively). Here's an example of how to access field data in PHP:

require_once("DB.php");
$dsn = "mysql://username:password@localhost/database";
$options = array(
    'debug'       => 2,
    'portability' => DB_PORTABILITY_ALL,
);
$db =& DB::connect($dsn, $options);
$db->setFetchMode(DB_FETCHMODE_ASSOC);
$res =& $db->query("SOME SQL STRING");
$row =& $res->fetchRow();
echo $row['field1'];

And here's how to do it using ADO in VBScript:

Dim conn, rs
Set conn = Server.CreateObject("ADODB.Connection")
Set rs = Server.CreateObject("ADODB.Recordset")
conn.ConnectionString = "some connection string"
Set rs.ActiveConnection = conn
rs.Open "SOME SQL STRING"
Response.Write rs.Fields("field1").Value

You can see the similarities between the two routines. First, you establish a connection with the database. Then, you send a query and receive a resultset. Just like ADO, the PEAR DB package provides an abstraction to all the lower-level mechanics involved with communicating with the database server.

If you're new to PEAR, then you'll want to know how to implement the packages on your own system. As a distribution system, PEAR makes packages easy to implement. I don't have much control over my hosted Web site, so I'm restricted to my own real estate on the virtual host via FTP and a host provider-supplied "control panel."

Before you install PEAR, copy the contents of this script to a PHP file on your host system. I created a directory under the default Web directory on my host called install, and copied the script to a file called go-pear.php. I changed the directory permissions to allow access for the installer script. Next, I navigated my browser to the go-pear.php installer page, and the script took care of the rest. Once it was done, I followed the link to the Web package installer, changed the configuration options (which I located by following the configuration link), and started installing packages with no problem.

Note: I ran the installer and my PHP scripts on a hosted site supporting PHP 4.3.8 and MySQL 4.0.20-standard. The server OS is Linux 2.4.21-15.ELsmp, and the Web server is Apache 1.3.31.

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