<?php
class DO_User {
    public $userId;
    public $firstName;
    public $lastName;
    public $email;

    // This function will perform a select on the table looking for a specific userId.
    public function get($userId)
    {
        $sql = 'SELECT * FROM User WHERE userId=' . mysql_escape_string($userId);
        $rs = mysql_query($sql);
        $row = mysql_fetch_array($rs);

        $this->userId    = $row['userId'];
        $this->firstName = $row['firstName'];
        $this->lastName  = $row['lastName'];
        $this->email     = $row['email']
    }
}
?>