高级 — 在连接字符串字段中指定正在 RAC 集群中运行的数据库的单客户端访问名 (Single Client Access Name, SCAN) ID。例如：
sales.example.com =(DESCRIPTION= (ADDRESS_LIST= (LOAD_BALANCE=on)(FAILOVER=ON) (ADDRESS=(PROTOCOL=tcp)(HOST=123.45.67.111)(PORT=1521)) (ADDRESS=(PROTOCOL=tcp)(HOST=123.45.67.222)(PORT=1521)) (ADDRESS=(PROTOCOL=tcp)(HOST=123.45.67.333)(PORT=1521))) (CONNECT_DATA=(SERVICE_NAME= salesservice.example.com)))