MySQL表值与php var相等（然后显示）

I have the following MySQL table and I would like to do that RVR11 (500) be equal with a php var $RVR11

I have this code but it doesnt work.

$servername = "localhost";
$username = "root";
$password = "";


$conn = new mysqli($servername, $username, $password);


if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
} 
echo "Connected successfully";


$price = mysql_query("SELECT RVR11 FROM tablename");
$result = mysql_fetch_array($RVR11);
echo $result['RVR11'];

Sorry about this beginner question.

You should choose a database before any queries, you can pass the fourth arguments to new mysqli constructor.