问ORA-12545:由于目标主机或对象不存在，连接失败- System.Data.OracleClient上没有错误

EN

{"ORA-12545: Connect failed because target host or object does not exist"}

using (OracleConnection con = new OracleConnection("Data Source=orac;User Id=SYSTEM; Password=Pass;"))
        {
            con.Open();
            Console.WriteLine("Connection opened");

            OracleCommand cmd2 = new OracleCommand("SELECT * FROM SYSTEM.TABLE", con);
            OracleDataReader oracleDataReader = cmd2.ExecuteReader();

            while (oracleDataReader.Read())
            {
                Console.WriteLine(oracleDataReader[0]);
            }
        }

# tnsnames.ora Network Configuration File: 
C:\app\UserName\product\11.2.0\dbhome_3\network\admin\tnsnames.ora
# Generated by Oracle configuration tools.

ORAC =
 (DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1522))
(CONNECT_DATA =
  (SERVER = DEDICATED)
  (SERVICE_NAME = orac.example.com)
)
 )

LISTENER_ORAC =
(ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1522))