exec sp_depends '已知表名'

------解决方案--------------------
如果查外健关系:  
create table t1(ID int primary key )  

create table t2(ID int constraint FK_t2 foreign key references t1(ID))  


select 
object_name(fkeyID),object_name(rkeyID) 
from 
sysforeignkeys 
where 
fkeyID=object_id( 't2 ')