Sql Server中通过父记录查找出所有关联的子记录（可查4级Sql代码）
select menu_id,menu_name,Father_Id from Sys_Menu where menu_id='18' or Father_Id=18 or -- 一级、二级Father_Id in (select menu_id from Sys_Menu a where menu_id='18' or Father_Id=18) or -- 三级father_id in (select menu_id from sys_menu where Father_Id in (select menu_id from Sys_Menu a where menu_id='18' or Father_Id=18)) -- 四级
select menu_id,menu_name,Father_Id from Sys_Menu where menu_id='18' or Father_Id=18 or -- 一级、二级
Father_Id in (select menu_id from Sys_Menu a where menu_id='18' or Father_Id=18) or -- 三级