sql跨数据库查询方法
http://www.cnblogs.com/xingluzhe/archive/2012/02/01/2334311.html
SELECT u_name
FROM OPENROWSET('sqloledb','DRIVER={SQL Server};SERVER=119.48.48.152;UID=y_ydgl;PWD=55555////\',DB.dbo.y_users) where u_name='1'
UNION all
SELECT u_name
FROM OPENROWSET('sqloledb','DRIVER={SQL Server};SERVER=119.48.48.152;UID=y_ydgl;PWD=55555////\',DB1.dbo.y_users) where u_name='1'