PHP SQL代码优化[关闭]

Question

I am learning the object oriented PHP. Now I have the mission to get a connection. I'd like to show my code and ask you for some optimization support. Maybe there are several absolutely wrong understood things. I don't hope so. I want to improve my design. In real the Constants of course have the rights values. BIG THANKS! :)

// index.php

<?php
require( dirname( __FILE__ ) . '/config.php' );
new db(DB_HOST, DB_USER, DB_PASSWORD, DB_DATABASE);
?>

// config.php

<?php
define('DB_HOST', 'host');
define('DB_USER', 'user');
define('DB_PASSWORD', 'password');
define('DB_DATABASE', 'database');

if (!defined('ABSPATH') )
    define('ABSPATH', dirname(__FILE__) . '/');

require_once(ABSPATH . '/includes/classes/db.class.php');
?>

// db.class.php

<?php
class db
{
    protected $db_host;
    protected $db_user;
    protected $db_password;
    protected $db_name;

    function __construct($dbHost, $dbUser, $dbPassword, $dbName)
    {
        global $mysqli;

        $this -> db_host       = $dbHost;
        $this -> db_user       = $dbUser;
        $this -> db_password   = $dbPassword;
        $this -> db_name       = $dbName;

        $this -> mysqli = new mysqli($this -> db_host, $this -> db_user, $this -> db_password, $this -> db_name);
        $mysqli = $this -> mysqli;
    }
}
?>

Answer 1

Here are some tips I found some time back, On the DB layer

Define connection as a static variable, to avoid connecting more than once

static $connection;

Try and connect to the database, if a connection has not been established yet, Create connection only once

if(!isset($connection)) {
     // Load configuration as an array. Use the actual location of your configuration file
    $config = parse_ini_file('../config.ini'); 
    $connection = mysqli_connect('localhost',$config['username'],$config['password'],$config['dbname']);
}

If connection was not successful, handle the error

if($connection === false) {
    // Handle error - notify administrator, log to a file, show an error screen, etc.
    return mysqli_connect_error(); 
}

Finally return connection

return $connection;

More info: https://www.binpress.com/tutorial/using-php-with-mysql-the-right-way/17