请问SQL~

请教SQL~~
请教SQL

表结构如：
Parent Child
 A B
 A D
 A F
 B T
 B S
 D H
 F M
 N B
 N L
 N Z
 L D
 L C
 Z D
 Z F

如何写SQL语句分别得到任何一个parent下的存在的亲子关系。
例如：
A下面存在的亲子关系有：
A - B
A - D
A - F
B - T
B - S
D - H
F - M


如何写SQL语句得到任何一个parent下的所有节点，直至根节点
例如：
A的子孙有：
B\T\S\D\H\F\M

如何写SQL语句得到任何一个child的所有祖先.
例如：
D的祖先有：
L/N/Z/A

谢谢~~~

[解决办法]
--根据子查父集
select * from tablename
start with child = 'F'
connect by prior child = parent
[解决办法]
D的长辈们

SQL code

with t as( select 'A' parent,'B' child from dual UNION    select 'A' parent,'D' child from dual UNION  select 'A' parent,'F' child from dual UNION  select 'B' parent,'T' child from dual UNION  select 'B' parent,'S' child from dual UNION  select 'D' parent,'H' child from dual UNION  select 'F' parent,'M' child from dual UNION  select 'N' parent,'B' child from dual UNION  select 'N' parent,'L' child from dual UNION  select 'N' parent,'Z' child from dual UNION  select 'L' parent,'D' child from dual UNION  select 'L' parent,'C' child from dual UNION  select 'Z' parent,'D' child from dual UNION  select 'Z' parent,'F' child from dual  )select distinct parent from t start with child='D'connect by child = prior parent;