if( !isset($_SESSION["p_id"])){
    echo "Please log in before attempting to rate messages";
    die();
    }
if( !isset($_POST["m_id"])){
    echo "Invalid message ID";
    die();
    }
if( !isset($_POST["rating"])){
    echo "Invalid rating";
    die();
    }

$link = connectDB();
$stmt = $link->prepare('SELECT rating FROM rate WHERE p_id =? AND m_id =?');
$stmt->bind_param('ss', $_POST["rating"], $_POST["m_id"]);
// execute query and display results
if (!$stmt->execute()){
        echo "Error executing prepared statement<br />";
        die();
    }

if($stmt->fetch()){
    if($DEBUG_MODE)
        echo "[DEBUG]There was a result. Run the update<br />";
}
else{ // no result. Insert it
    if($DEBUG_MODE){
        echo "[DEBUG]There was no result. Insert the rating<br />";
        echo $_SESSION["p_id"].' '.$_POST["m_id"].' '.$_POST["rating"];
        }

    $stmt = $link->prepare('INSERT INTO rating (p_id, m_id, rating) VALUES (?, ?, ?)');
    // The following line gives an error of: Call to a member function bind_param() on a non-object
    $stmt->bind_param('sii', $_SESSION["p_id"], $_POST["m_id"], $_POST["rating"] );
    if (!$stmt->execute()){
        echo "Error executing prepared statement<br />";
        echo($link->error);
        echo "<br />".$_SESSION["p_id"];
    }
}