string cosn = "Data Source=172.20.65.236;User Id=bjmedicare_qy;Password=bjmedicare_qy";
            string sql = "select * from test_n";
            OracleConnection conn = new OracleConnection(cosn);
            OracleCommand cmd = new OracleCommand(sql, conn);
            OracleDataAdapter adp = new OracleDataAdapter(cmd);
            DataSet dsRet = new DataSet();
            adp.Fill(dsRet);
            adp.Dispose();
            conn.Close();