---------创建dblink
create public  database link misa239 
　　 connect to sandtms identified by sandtms 
　　 using '(DESCRIPTION = 
　　 (ADDRESS_LIST = 
　　 (ADDRESS = (PROTOCOL = TCP)(HOST = 172.28.250.239)(PORT = 1521)) 
　　 ) 
　　 (CONNECT_DATA = 
　　 (SERVICE_NAME = ORCL) 
　　 ) 
　　 )';

-------删除dblink
DROP PUBLIC DATABASE LINK MISA239