<?php

// guardando hash da senha
$query  = sprintf("INSERT INTO users(name,pwd) VALUES('%s','%s');",
            pg_escape_string($username), md5($password));
$result = pg_query($connection, $query);

// consultando se o usuário enviou a senha correta
$query = sprintf("SELECT 1 FROM users WHERE name='%s' AND pwd='%s';",
            pg_escape_string($username), md5($password));
$result = pg_query($connection, $query);

if (pg_num_rows($result) > 0) {
    echo 'Bem vindo, $username!';
} else {
    echo 'Autenticação falhou para o $username.';
}

?>