with name of you cte>(column names>)
as(
actual query>
)
select * from name of your cte>

--菜單目錄結構表 
create table tb_menu( 
 id int not null, --主鍵id 
title varchar(50), --標題 
 parent int --parent id 
); 
--父菜單 
insert into tb_menu(id, title, parent) values(1, '父菜單1',null); 
insert into tb_menu(id, title, parent) values(2, '父菜單2',null); 
insert into tb_menu(id, title, parent) values(3, '父菜單3',null); 
insert into tb_menu(id, title, parent) values(4, '父菜單4',null); 
insert into tb_menu(id, title, parent) values(5, '父菜單5',null); 
--一級菜單 
insert into tb_menu(id, title, parent) values(6, '一級菜單6',1); 
insert into tb_menu(id, title, parent) values(7, '一級菜單7',1); 
insert into tb_menu(id, title, parent) values(8, '一級菜單8',1); 
insert into tb_menu(id, title, parent) values(9, '一級菜單9',2); 
insert into tb_menu(id, title, parent) values(10, '一級菜單10',2); 
insert into tb_menu(id, title, parent) values(11, '一級菜單11',2); 
insert into tb_menu(id, title, parent) values(12, '一級菜單12',3); 
insert into tb_menu(id, title, parent) values(13, '一級菜單13',3); 
insert into tb_menu(id, title, parent) values(14, '一級菜單14',3); 
insert into tb_menu(id, title, parent) values(15, '一級菜單15',4); 
insert into tb_menu(id, title, parent) values(16, '一級菜單16',4); 
insert into tb_menu(id, title, parent) values(17, '一級菜單17',4); 
insert into tb_menu(id, title, parent) values(18, '一級菜單18',5); 
insert into tb_menu(id, title, parent) values(19, '一級菜單19',5); 
insert into tb_menu(id, title, parent) values(20, '一級菜單20',5); 
--二級菜單 
insert into tb_menu(id, title, parent) values(21, '二級菜單21',6); 
insert into tb_menu(id, title, parent) values(22, '二級菜單22',6); 
insert into tb_menu(id, title, parent) values(23, '二級菜單23',7); 
insert into tb_menu(id, title, parent) values(24, '二級菜單24',7); 
insert into tb_menu(id, title, parent) values(25, '二級菜單25',8); 
insert into tb_menu(id, title, parent) values(26, '二級菜單26',9); 
insert into tb_menu(id, title, parent) values(27, '二級菜單27',10); 
insert into tb_menu(id, title, parent) values(28, '二級菜單28',11); 
insert into tb_menu(id, title, parent) values(29, '二級菜單29',12); 
insert into tb_menu(id, title, parent) values(30, '二級菜單30',13); 
insert into tb_menu(id, title, parent) values(31, '二級菜單31',14); 
insert into tb_menu(id, title, parent) values(32, '二級菜單32',15); 
insert into tb_menu(id, title, parent) values(33, '二級菜單33',16); 
insert into tb_menu(id, title, parent) values(34, '二級菜單34',17); 
insert into tb_menu(id, title, parent) values(35, '二級菜單35',18); 
insert into tb_menu(id, title, parent) values(36, '二級菜單36',19); 
insert into tb_menu(id, title, parent) values(37, '二級菜單37',20); 
 
--三級菜單 
insert into tb_menu(id, title, parent) values(38, '三級菜單38',21); 
insert into tb_menu(id, title, parent) values(39, '三級菜單39',22); 
insert into tb_menu(id, title, parent) values(40, '三級菜單40',23); 
insert into tb_menu(id, title, parent) values(41, '三級菜單41',24); 
insert into tb_menu(id, title, parent) values(42, '三級菜單42',25); 
insert into tb_menu(id, title, parent) values(43, '三級菜單43',26); 
insert into tb_menu(id, title, parent) values(44, '三級菜單44',27); 
insert into tb_menu(id, title, parent) values(45, '三級菜單45',28); 
insert into tb_menu(id, title, parent) values(46, '三級菜單46',28); 
insert into tb_menu(id, title, parent) values(47, '三級菜單47',29); 
insert into tb_menu(id, title, parent) values(48, '三級菜單48',30); 
insert into tb_menu(id, title, parent) values(49, '三級菜單49',31); 
insert into tb_menu(id, title, parent) values(50, '三級菜單50',31); 
commit; 

--查詢樹狀結構某節點(44)的上級所有根節點 
 
with cte_parent(id,title,parent) 
 
as 
 
( 
 
  --起始條件 
 
  select id,title,parent 
 
  from tb_menu 
 
  where id = 44  --列出子節點查詢條件 
 
  union all 
 
  --遞歸條件 
 
  select a.id,a.title,a.parent 
 
  from tb_menu a 
 
  inner join  
 
  cte_parent b     --執行遞歸，這里就要理解下了  
 
  on a.id=b.parent  
 
)             
 
select * from cte_parent; 

--查詢樹狀結構某節點下的所有子節點( 
 
with cte_child(id,title,parent,level) 
 
as 
 
( 
 
  --起始條件 
 
  select id,title,parent,0 as level 
 
  from tb_menu 
 
  where id = 6--列出父節點查詢條件 
 
  union all 
 
  --遞歸條件 
 
  select a.id,a.title,a.parent,b.level+1 
 
  from tb_menu a 
 
  inner join  
 
  cte_child b 
 
  on ( a.parent=b.id)  
 
) 
 
select * from cte_child;