可以使用dblink做跨库查询操作

配置一
create database link dcmdb connect to dcmdb identified by dcmoptr using 'zbcdb3' ;
select * from tabname@dcmdb where 1=1;

配置二
create database link to_bylw3 connect to bcp_fj identified by bcp123 using '(DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.2.172)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVICE_NAME = szqdyxbf8)    
    )
  )';