Sql语句之递归查询

直接进入正题

比如一个表，有id和pId字段，id是主键，pid表示它的上级节点，表结构和数据：

 

CREATE TABLE [aaa](
 [id] [int] NULL,
 [pid] [int] NULL,
 [name] [nchar](10)
)
GO
INSERT INTO aaa VALUES(1,0,'a')
INSERT INTO aaa VALUES(2,0,'b')
INSERT INTO aaa VALUES(3,1,'c')
INSERT INTO aaa VALUES(4,1,'d')
INSERT INTO aaa VALUES(5,2,'e')
INSERT INTO aaa VALUES(6,3,'f')
INSERT INTO aaa VALUES(7,3,'g')
INSERT INTO aaa VALUES(8,4,'h')
GO
--下面的Sql是查询出1结点的所有子结点
with my1 as(select * from aaa where id = 1
 union all select aaa.* from my1, aaa where my1.id = aaa.pid
)
select * from my1 --结果包含1这条记录，如果不想包含，可以在最后加上:where id <> 1
--下面的Sql是查询出8结点的所有父结点
with my1 as(select * from aaa where id = 8
 union all select aaa.* from my1, aaa where my1.pid = aaa.id
)
select * from my1;
 --下面是递归删除1结点和所有子结点的语句：
with my1 as(select * from aaa where id = 1
   union all select aaa.* from my1, aaa where my1.id = aaa.pid
)
delete from aaa where exists (select id from my1 where my1.id = aaa.id)

二：

SQLserver2008使用表达式递归查询

--由父项递归下级
with cte(id,parentid,text)
as
(--父项
select id,parentid,text from treeview where parentid = 450
union all
--递归结果集中的下级
select t.id,t.parentid,t.text from treeview as t
inner join cte as c on t.parentid = c.id
)
select id,parentid,text from cte
--由子级递归父项
with cte(id,parentid,text)
as
(--下级父项
select id,parentid,text from treeview where id = 450
union all
--递归结果集中的父项
select t.id,t.parentid,t.text from treeview as t
inner join cte as c on t.id = c.parentid
)
select id,parentid,text from cte