I'm a beginner PHP developer and it's my first time using MySQLi. I'm not sure if this is a correct implementation of the connection and query because some people defend this method and some others not. I need a solid implementation for heavy database usage.
Connection:
class bbddConnection {
private $_host = 'localhost';
private $_username = 'username';
private $_password = 'password';
private $_db_name = 'DBNAME';
private $_mysqli = NULL;
private static $_instance = NULL;
private function __construct() {
$this->connection();
}
public static function get_instance() {
if (!isset(self::$_instance)) {
//echo "Creating new instance.\n";
$class_name = __CLASS__;
self::$_instance = new $class_name;
}
return self::$_instance;
}
private function connection() {
//echo "Creating new connection.\n";
try {
//The mysqli object will be created once and only once
if (!$this->_mysqli instanceof mysqli) {
$this->_mysqli = new mysqli($this->_host, $this->_username, $this->_password);
}
if ($this->_mysqli->connect_errno) {
throw new Exception('An error occured: ' . $this->_mysqli->connect_error);
} else {
$this->select_db();
}
} catch (Exception $e) {
echo $e->getMessage() . "\n";
}
}
private function select_db() {
//echo "Selecting database.\n";
try {
$this->_mysqli->select_db($this->_db_name) or die('Could not find database');
} catch (Exception $e) {
echo $e->getMessage() . "\n";
}
}
public function query($query) {
if (!isset($query))
return;
//echo "Prevent SQL Injection. \n"
$query = $this->_mysqli->real_escape_string($query);
return $this->_mysqli->query($query);
}
public function stmt_init() {
return $this->_mysqli->stmt_init();
}
public function __destruct() {
if ($this->_mysqli instanceof mysqli) {
$this->_mysqli->close();
}
}
private function __clone() {
trigger_error('Clone is not allowed.', E_USER_ERROR);
}
private function __wakeup() {
trigger_error('Unserializing is not allowed.', E_USER_ERROR);
}
}
Query:
class gestorUsuarios {
private $db;
public function __construct() {
$this->db = bbddConnection::get_instance();
}
/**
* Returns the Name of the user according his ID
* @param int id
* @return string Nombre, if an error occurred.
* returns <b>FALSE</b>
*/
function getUserName($id)
{
$stmt = $this->db->stmt_init();
if ($stmt->prepare("Select Nombre from usuarios where id = ?")) {
$name = '';
$stmt->bind_param('i', $id);
$stmt->execute();
$stmt->bind_result($name);
while ($stmt->fetch())
$nombre = $name;
$stmt->close();
return $nombre;
} else {
return false;
}
}
/**
* Edit the Name of the user according his ID
* @param String Nombre, int id
* @return Boolean if an error occurred.
* returns <b>FALSE</b>, else returns <b>TRUE</b>
*/
function setUserName($nombre, $id)
{
$stmt = $this->db->stmt_init();
if ($stmt->prepare("UPDATE usuarios SET Nombre=? WHERE id =?")) {
$stmt->bind_param('si', $nombre, $id);
$stmt->execute();
$stmt->close();
return true;
} else {
return false;
}
}
}
