如何解决多个SQL数据库合并显示数据

如果三库同机: SQL code? select * from dbnamea.dbo.tb union all select * from dbnameb.dbo.tb union all select * from dbnamec.dbo.tb 如果三库不同机,注册后. SQL code? select * from machinenamea.dbnamea.dbo.tb union all select * from machinenameb.dbna