SQL 找路线问题（查找 从A到 I怎么走路线）

查找 从A到 I怎么走路线

create table #y([f1] varchar(1),[f2] varchar(1))
insert #y 
select 'A','B' union all 
select 'A','F' union all 
select 'A','G' union all 
select 'B','C' union all 
select 'B','G' union all 
select 'B','H' union all 
select 'B','A' union all 
select 'C','B' union all 
select 'C','H' union all 
select 'C','I' union all 
select 'C','D' union all 
select 'D','C' union all 
select 'D','I' union all 
select 'D','J' union all 
select 'E','J' union all 
select 'E','D' union all 
select 'F','A' union all 
select 'F','G' union all 
select 'G','A' union all 
select 'G','B' union all 
select 'G','H' union all 
select 'G','F' union all 
select 'H','G' union all 
select 'H','B' union all 
select 'H','C' union all 
select 'H','I' union all 
select 'I','H' union all 
select 'I','C' union all 
select 'I','D' union all 
select 'I','F' union all 
select 'J','I' union all 
select 'J','D' union all 
select 'J','E' 
GO 
 WITH tb_a AS( 
    SELECT #y.f1,#y.f2,[result]=CAST(#y.f1 +'->' + #y.f2 AS VARCHAR(1500)) FROM #y WHERE #y.f1='a' 
    UNION ALL    
    SELECT #y.f1,#y.f2,[result]=CAST([result]+ '->' + #y.f2 AS VARCHAR(1500)) FROM tb_a a INNER JOIN #y ON a.f2=#y.f1  WHERE charIndex(#y.f2,a.[result])<1
 )
 SELECT * FROM tb_a WHERE result LIKE '%i'