ORA-12514 TNS:listener does not currently know of service requested in connect d

第一步：

在数据库中查询数据库服务名称

select value from v$parameter where name='service_names'

第二步：

port后为查询到的服务名称

sqlplus username/passwd@IP:port/servicename

或者修改tnsnames.ora中的SERVICE_NAME

TEST =
   (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = *<validhost>*)(PORT = *<validport>*))
    )
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = *<servicenamefromDB>*)
    )
)