In addition to the above:
// Create a new mysqli object which is an interface to be specific
$connection = new mysqli('server', 'username', 'password', 'database');
// Invoke the prepare() method with the 'prepared' query string
$result = $connection->prepare("SELECT products, usertype, special_pricing_user, special_pricing, pcconly FROM users WHERE username = ?");
// Bind $username to the '?' value field that you see above
$result->bind_param("s", $username);
// Execute the query
$result->execute();
// Fetch the results into the $result array
$result->bind_result($userproducts, $usertype, $special_pricing_user, $special_pricing, $pcconly);
// Loop through the results
while ($row = $result->fetch()) {
//
}
If that's too layman for you, then ask for specifics.