how to connect php to postgresql

<?php
$dbconn = pg_connect("dbname=demo");
//connect to a database named "demo"

$dbconn3 = pg_connect("host=sheep port=5432 dbname=demo user=lamb password=foo");
//connect to a database named "demo" on the host "sheep" with a username and password

$conn_string = "host=sheep port=5432 dbname=test user=lamb password=bar";
$dbconn4 = pg_connect($conn_string);
//connect to a database named "test" on the host "sheep" with a username and password

?>