Opencart 1.4.9 from mysql to mysqli - php

Question

My host has upgraded it's PHP to version 5.5 and MySQL to 5.6.
We are still using Opencart 1.4.9.6 and cannot upgrade immediately as the store is live and we have a lot of own modifications.
Right now we are unable to view our administration area and this message is shown on top of all of our pages:
Deprecated: mysql_connect(): The mysql extension is deprecated and will be removed in the future: use mysqli or PDO instead in /home/public_html/system/database/mysql.php on line 8
How should we proceed if we want the message to disappear and be able to log in to our admin pages? Is it possible to just change mysql_connect to mysqli?
Here is the code which is used in mysql.php:
<?php
final class MySQL {
private $connection;
public function __construct($hostname, $username, $password, $database) {
if (!$this->connection = mysql_connect($hostname, $username, $password)) {
exit('Error: Could not make a database connection using ' . $username . '#' . $hostname);
}
if (!mysql_select_db($database, $this->connection)) {
exit('Error: Could not connect to database ' . $database);
}
mysql_query("SET NAMES 'utf8'", $this->connection);
mysql_query("SET CHARACTER SET utf8", $this->connection);
// mic changed 20100824 instead of SET NAMES and CHARACTER SET
// see: http://at2.php.net/manual/en/function.mysql-set-charset.php
//mysql_set_charset( 'utf8', $this->connection );
mysql_query("SET CHARACTER_SET_CONNECTION=utf8", $this->connection);
mysql_query("SET SQL_MODE = ''", $this->connection);
}
public function query($sql) {
$resource = mysql_query($sql, $this->connection);
if ($resource) {
if (is_resource($resource)) {
$i = 0;
$data = array();
while ($result = mysql_fetch_assoc($resource)) {
$data[$i] = $result;
$i++;
}
mysql_free_result($resource);
$query = new stdClass();
$query->row = isset($data[0]) ? $data[0] : array();
$query->rows = $data;
$query->num_rows = $i;
unset($data);
return $query;
} else {
return TRUE;
}
} else {
exit('Error: ' . mysql_error($this->connection) . '<br />Error No: ' . mysql_errno($this->connection) . '<br />' . $sql);
}
}
public function escape($value) {
return mysql_real_escape_string($value, $this->connection);
}
public function countAffected() {
return mysql_affected_rows($this->connection);
}
public function getLastId() {
return mysql_insert_id($this->connection);
}
public function __destruct() {
mysql_close($this->connection);
}
}
?>

Answer 1

How should we proceed if we want the message to disappear and be able to log in to our admin pages?
Open the file <OC_ROOT>/system/startup.php
Change this line:
error_reporting(E_ALL)
to
error_reporting(E_ALL ^ E_DEPRECATED) , now all deprecation warnings will disappear
Is it possible to just change mysql_connect to mysqli?
I don't know if OC 1.4.9 has a built in driver for mysqli, to check that, open the directory <OC_ROOT>/system/database and make sure that there is a file named mysqli.php, if it's there, then apply the following steps: (if not, you need to change all mysql_* functions in the project)
Open configuration files <OC_ROOT>/config.php and <OC_ROOT>/admin/config.php
Change this line:
define('DB_DRIVER', 'mysql')
to
define('DB_DRIVER', 'mysqli')

Answer 2

Is it possible to just change mysql_connect to mysqli?
No, that's not enough. You have to change all functions started from mysql_. It is not that hard, though. All you need is programmer who is given a hour of time.
How should we proceed if we want the message to disappear
Just disable it.
error_reporting(E_ALL & ~E_DEPRECATED);
and be able to log in to our admin pages?
That's hardest question of them all. And you better ask aforementioned programmer for this, as there could be other errors that prevent you from logging in.