PHP - MySQL - Testing POC

<?php


if($_POST['select'] and $_SERVER['REQUEST_METHOD'] == "POST")
{
    //select();
    echo "select click";
}


if($_POST['insert'] and $_SERVER['REQUEST_METHOD'] == "POST")
{
    //get data from from elements
    // testing data
    $connClass = new dbConnection();

    $userName = "Name Test";
    $phoneNum = "(405)555-1234";
    $address = "123 fake st";

    $sql = sprintf("INSERT INTO php_test (userName, phone, address)
        VALUES ('%s', '%s', '%s')", $userName, $phoneNum, $address);

    $connClass->insertData($sql);
}



class dbConnection
{

    private $servername = "127.0.0.1";
    private $username = "root";
    private $password = "password";
    private $dbname = "php_local_testing";

    public $link;

    private $result;

    function __construct()
    {
        // Create connection
        $this->link = new mysqli($this->servername, $this->username, $this->password, $this->dbname);

        // Check connection
        if ($this->link->connect_errno)
        {
            echo "Connection Error\n";
            die("Connection failed: " . $this->link->connect_error);
        }


        return $this->link;
    }


    function insertData($sql)
    {

        if ($this->link->query($sql) === TRUE)
        {
            echo "New record created successfully";
        } else {
            echo "Error: " . $sql . "<br>" . $this->link->error;
        }


    }


    function __destruct()
    {
        $this->link->close();
    }

}


?>