所以，觉得有必要记录下来，这样以后再次碰到这类问题，也能从中获取解答的思路。

问题：怎么循环查询一个表 用递归吗？

有2张表B1和B2，B1是主表，

B1的BID是对应B2的B2ID，

B1和B2d是一对多的关系，

B2ID下还有以它为父节点的数据，测试数据如下：

B1

BID sname

1266   JM          

1286   DM

......        

B2

B2ID SID

1266   DH1500          

1266   DH1592

1266   DH1595

DH1500   E89876

DH1500   E89896

联合2表查询，要得到这样的结果：

MainID SID

1266 DH1500

1266 DH1592

1266 DH1595

DH1500   E89876

DH1500   E89896

这个怎么查？求解

我的方法：

if object_id('[B1]') is not null drop table [B1]





go 





create table [B1]([BID] varchar(6),[sname] varchar(2))





insert [B1]





select '1266','JM' union all





select '1286','DM'





 





if object_id('[B2]') is not null drop table [B2]





go 





create table [B2]([B2ID] varchar(6),[SID] varchar(6))





insert [B2]





select '1266','DH1500' union all





select '1266','DH1592' union all





select '1266','DH1595' union all





select 'DH1500','E89876' union all





select 'DH1500','E89896'





go





 





 





 





--1.定义表变量





 





DECLARE @a VARCHAR(10)





SET @a='JM'





 





declare @tb table





([B2ID] varchar(6),





[SID] varchar(6),





level int       --层级





)





 





 





--2.递归开始  





insert into @tb 





SELECT a.* ,1 [level]





FROM b2 a LEFT JOIN b2 b ON b.SID=a.b2id





WHERE b.b2id IS NULL AND b.SID IS NULL AND a.b2id IN (SELECT bid FROM b1 WHERE [sname]=@a)





 





 





--3.递归的过程





while @@ROWCOUNT > 0





begin





    





    insert into @tb





	select b.[B2ID],b.[SID],level + 1





	from @tb t





	inner join B2 b





			on b.b2id =t.SID





    where not exists(select 1 from @tb t2 





                     where t.level < t2.level)





end





 





 





--4.最后查询





SELECT b2id MainID    ,SID





 FROM  @tb





/*





MainID	SID





1266	DH1500





1266	DH1592





1266	DH1595





DH1500	E89876





DH1500	E89896





*/