PHP7 - MYSQLI CONNECT

// Open Connection
$con = @mysqli_connect('localhost', 'root', '', 'product');

if (!$con) {
    echo "Error: " . mysqli_connect_error();
    exit();
}

// Some Query
$sql    = 'SELECT * FROM product';
$query  = mysqli_query($con, $sql);
while ($row = mysqli_fetch_array($query))
{
    echo $row['id'];
}

// Close connection
mysqli_close ($con);