PHP・MySQL 最小値・最大値

$dbh = new PDO($DSN , $DBUSER , $DBPASS);

$query="select min(id) as id_min, max(id) as id_max from test";

$stmt = $dbh->query($query);

$stmt->execute();

$result = $stmt->fetch( PDO::FETCH_ASSOC );

$min = $result['id_min'];

$max = $result['id_max'];