$sql = "SELECT ".$db_table_prefix."Users.Group_ID,
	".$db_table_prefix."Groups.* FROM ".$db_table_prefix."Users
	INNER JOIN ".$db_table_prefix."Groups ON ".$db_table_prefix."Users.Group_ID = ".$db_table_prefix."Groups.Group_ID
	WHERE User_ID  = '".$db->sql_escape($this->user_id)."'
	AND
	".$db_table_prefix."Users.Group_ID = '".$db->sql_escape($db->sql_escape($id))."'
	LIMIT 1
	";