$dbconnSrc = pg_connect("host=$dbhost dbname=$dbname user=$dbuser password=$dbpass") or die ("Could not connect");

$sql="select area, radius from circle where level>50;

$res = pg_query($dbconnSrc, $sql);
var_dump(isset($res));
echo "$resn";
while($row = pg_fetch_array($res, NULL, PGSQL_ASSOC))
{
    $radius=$row["radius"];
    print "radius is $radiusn";
    if (isset($radius)){
        echo "NOT NULLn";
    }
    else
    {
         echo "NULLn";
    }
}