how to implement shopping cart in php code example

Example: shopping cart php pdo mysql ajax

<?php
	/**
	 * @package Cart class
	 *
	 * @author TechArise Team
	 *
	 * @email  [email protected]
	 *   
	 */
 
	include("DBConnection.php");
	class Cart 
	{
 
	    protected $db;
	    private $_sku;
	    public function setSKU($sku) {
	        $this->_sku = $sku;
	    }
 
	    public function __construct() {
	        $this->db = new DBConnection();
	        $this->db = $this->db->returnConnection();
	    }
 
	    // getAll Product
	    public function getAllProduct() {
	    	try {
	    		$sql = "SELECT * FROM products";
			    $stmt = $this->db->prepare($sql);
 
			    $stmt->execute();
			    $result = $stmt->fetchAll(\PDO::FETCH_ASSOC);
	            return $result;
			} catch (Exception $e) {
			    die("Oh noes! There's an error in the query!");
			}
	    }
 
	    // get Student
	    public function getProduct() {
	    	try {
	    		$sql = "SELECT * FROM products WHERE sku=:sku";
			    $stmt = $this->db->prepare($sql);
			    $data = [
			    	'sku' => $this->_sku
				];
			    $stmt->execute($data);
			    $result = $stmt->fetch(\PDO::FETCH_ASSOC);
	            return $result;
			} catch (Exception $e) {
			    die("Oh noes! There's an error in the query!");
			}
	    }
 
	}
	?>