创建dblink

 CREATE public database link test_link 
 CONNECT TO scott IDENTIFIED 
 BY tiger using '(DESCRIPTION = 
 (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 127.0.0.1)(PORT = 1521)) ) 
 (CONNECT_DATA = (SERVICE_NAME = LEE) ) )'; 
 --使用 select ename from emp@test_link; 
 --删除 drop public database link TEST_LINK;