function getRoles($rolename = '')
{
$sql = '
SELECT rolname, rolsuper, rolcreatedb, rolcreaterole, rolinherit,
rolcanlogin, rolconnlimit, rolvaliduntil, rolconfig
FROM pg_catalog.pg_roles';
if ($rolename) {
$sql .= " WHERE rolname!='{$rolename}'";
}
$sql .= ' ORDER BY rolname';
return $this->selectSet($sql);
}