Databse Connection

Lets say you have a file named db.php in your file directory. This is all you need in there unless you created a different class that extends the MySQLi :)

<?php
	$mysqli = new mysqli('localhost','username','password','database');
?>

It basically sets “$mysqli” variable to the connection of your database. This is the beauty of mysqli, all you need to do is just set your connection and you have your database class.

Class

Next up is your class. Lets say you have a class named books which gets the records for a book from a table called books from your database.
I saved this file as book.php in my file directory

<?php
class books{
	public $error;
	function __construct($mysqli){}

	function get_book($id){
		global $mysqli;
		if($result = $mysqli->query("SELECT* from books where book_id='$id'")){
			$row=$result->fetch_object();
			return $row;
		}else{
			$this->error = $mysqli->error;
		}

	}
}
?>

Now to explain the code;

Constructor

Following line requires you to send the mysqli connection you created earlier in your db.php. If you want you can have more in your constructor class obviously but in this example I didn’t need to put anything in there. More on Constructors and Destructors

	function __construct($mysqli){}

get_book function:

You need to set your $mysqli variable to be global so you can use it in the function. You accomplish that by just “global $mysqli;” line. If you don’t need a database connection in the function you do not need to set this.



The rest of the function is just basic querying and getting results.

Using the class

In your index.php include both of these files and then assign your class to a variable to be accessed. Notice that we are sending in the $mysqli variable in to the class.

include "db.php";
include "book.php";
$my_book_class = new books($mysqli);