new-wpdb.php

<?php
// user, pass, db name, host
$db = new wpdb( 'root', 'password', 'dbname', 'localhost' );

// insert some data
if ( $db->insert( 'company_contacts', array(
    'first_name' => 'Andy',
    'last_name' => 'Stratton',
    'email_address' => '[email protected]'
));

// retrieve a record
$user = $db->get_row( "SELECT * FROM company_contacts WHERE first_name = 'Andy'" );

echo '<p>' . $user->first_name . ' ' . $user->last_name . ' is in our database.</p>';

// retrieve a record set, useful for searches
$users = $db->get_results( "SELECT * FROM company_contacts WHERE first_name = 'Andy'" );
if ( count( $users ) > 0 ) )
{
    foreach ( $users as $user )
        echo '<p>' . $user->first_name . ' ' . $user->last_name . ' is in our database.</p>';
}


// retrieve a value
$email = $db->get_var( "SELECT email_address FROM company_contacts WHERE last_name = 'Stratton'" );
echo '<p>Email Address: ' . $email . '</p>';

// preparing statements based on user input
// assuming form submits to http://www.mysite.com/?fname=Andy&lname=Stratton

$input = array( $_GET['fname'], $_GET['lname'] );

// prepare our statement, %s denotes a string, 
// %d denotes an integer, %f denotes a floating point number
$sql = $db->prepare( "SELECT * FROM company_contacts WHERE first_name = %s AND last_name = %s", $input );

// $sql now has safe versions of our input strings inserted
// and is safe to query
$results = $db->get_results( $sql );