select b.company,a.m_affair from db2 a inner join db1 b
on b.id=a.companyid

------解决方案--------------------
SQL code

select a.company,b.m_affair from db1.dbo.tb_name a join db2.dbo.tb2_name b on a.id=b.companyid
--前提是先建立服务器DB之间的链接

------解决方案--------------------
这样应该也可以的

select a.company,b.m_affair from db1 a ,db2 b
where a.id=b.id