prova cosi:

codice:
<?php
$conn = pg_connect("host=localhost port=5432 dbname=postgres user=postgres password=xxx");
if (!$conn)
{
	echo "Connection to DB failed";
	exit; 
}
else
{
	$nome = $_POST["nome"]; 
	$cognome =$_POST["cognome"];
	$email = $_POST["email"];
	$psw =$_POST['psw']; 
	$query = "INSERT INTO Utente(nome,cognome, email, psw)VALUES('$nome','$cognome', '$email','$psw')";
	$result = pg_query($conn,$query);
	if(!$result)
	{
		exit("Errore nella query: " . pg_last_error ($conn));
	}
	pg_close($db);
}
?>