PHP OOP Login System

<?php
class Session {

    function __construct() {
        //start a new session
        $_SESSION["suppLogin"] = "guest";
    }

    function logIn($user) {
        $_SESSION["suppLogin"] = $user;
    }

    function verifyLogin($user, $pass) {
        $hash = hash('sha256',strtoupper($user)." insert salt here ".md5(strtolower($pass)));

        $mysqli = new mysqli("127.0.0.1","root"," hidden "," hidden ");
        if($mysqli->connect_errno){
            echo "Failed to connect to MySQL: (" . $mysqli->connect_errno . ") " . $mysqli->connect_error;
            return false;
        }

        if(!($stmt = $mysqli->prepare("SELECT * FROM users WHERE username=(?) && password=(?)"))){
            echo "Query preparation failed: (" . $mysqli->errno . ") " . $mysqli->error;
            return false;
        }

        if(!$stmt->bind_param("ss",$user,$hash)){
            echo "Failed to bind parameters: (" . $mysqli->errno . ") " . $mysqli->error;
            return false;
        }

        if(!$stmt->execute()){
            echo "Failed to execute statement: (" . $mysql->errno . ") " . $mysqli->error;
            return false;
        }

        $stmt->store_result();

        if($stmt->num_rows() != 1){
            echo "The information you provided was unable to authenticate your credentials. <br />";
            return false;
        }

        return true;
    }
}
?>