OpenCart PDO Database Adapter

mpdo.php

<?php
/**
 *   i changed class name as mPDO because, give me an error
 *
 *    " Fatal error: Cannot redeclare class pdo. If this code worked without the Zend Optimizer+,
 *      please set zend_optimizerplus.dups_fix=1 in your php.ini "
 */

class Mpdo
{
    private $pdo = null;
    private $statement = null;

    public function __construct($hostname, $username, $password, $database, $port = "3306")
    {

        try {
            $this->pdo = new PDO("mysql:host=" . $hostname . ";port=" . $port . ";dbname=" . $database, $username, $password);
        } catch (PDOException $e) {
            trigger_error(
                'Error: Could not make a database link ( ' . $e->getMessage() . '). Error Code : ' . $e->getCode(
                ) . ' <br />'
            );
        }

        $this->pdo->exec("SET NAMES 'utf8'");
        $this->pdo->exec("SET CHARACTER SET utf8");
        $this->pdo->exec("SET CHARACTER_SET_CONNECTION=utf8");
        $this->pdo->exec("SET SQL_MODE = ''");

    }

    public function getPdo()
    {
        return $this->pdo;
    }

    public function prepare($sql)
    {
        $this->statement = $this->pdo->prepare($sql);
    }

    public function bindParam($parameter, $variable, $data_type = PDO::PARAM_STR, $length = 0)
    {
        if ($length) {
            $this->statement->bindParam($parameter, $variable, $data_type, $length);
        } else {
            $this->statement->bindParam($parameter, $variable, $data_type);
        }
    }

    public function execute()
    {
        try {
            if ($this->statement && $this->statement->execute()) {
                $data = array();
                while ($row = $this->statement->fetch(PDO::FETCH_ASSOC)) {
                    $data[] = $row;
                }
                $result = new stdClass();
                $result->row = (isset($data[0]) ? $data[0] : array());
                $result->rows = $data;
                $result->num_rows = $this->statement->rowCount();
            }
        } catch (PDOException $e) {
            trigger_error('Error: ' . $e->getMessage() . ' Error Code : ' . $e->getCode() . ' <br />' . $sql);
            exit();
        }
    }

    public function query($sql, $params = array())
    {
        $this->statement = $this->pdo->prepare($sql);
        $result = false;

        try {
            if ($this->statement && $this->statement->execute($params)) {
                $data = array();

                while ($row = $this->statement->fetch(PDO::FETCH_ASSOC)) {
                    $data[] = $row;
                }

                $result = new stdClass();
                $result->row = (isset($data[0]) ? $data[0] : array());
                $result->rows = $data;
                $result->num_rows = $this->statement->rowCount();
            }
        } catch (PDOException $e) {
            trigger_error('Error: ' . $e->getMessage() . ' Error Code : ' . $e->getCode() . ' <br />' . $sql);
            exit();
        }

        if ($result) {
            return $result;
        } else {
            $result = new stdClass(); // to handle older opencart actions
            $result->row = array(); // to handle older opencart actions
            $result->rows = array(); // to handle older opencart actions
            $result->num_rows = 0; // to handle older opencart actions
            return $result; // should be false
        }

    }

    // From http://www.php.net/manual/de/function.mysql-real-escape-string.php#98506
    public function escape($value)
    {
        // Maybe we should use quote for this.
        $search = array("\\", "\0", "\n", "\r", "\x1a", "'", '"');
        $replace = array("\\\\", "\\0", "\\n", "\\r", "\Z", "\'", '\"');
        return str_replace($search, $replace, $value);
    }

    public function countAffected()
    {
        if ($this->statement) {
            return $this->statement->rowCount();
        } else {
            return 0;
        }
    }

    public function getLastId()
    {
        return $this->pdo->lastInsertId();
    }

    public function __destruct()
    {
        $this->pdo = null;
    }
}