c#代码如下
DbConnection connection = providerFactory.CreateConnection();
            DbCommand command = providerFactory.CreateCommand();
            connection.ConnectionString = ConnectionString;
            command.CommandText = sql;
            command.CommandType = commandType;
            command.Connection = connection;
            try
                {
                    command.Connection.Open();
                    using (DbDataReader reader = command.ExecuteReader())//这里报异常
                    {.....此处省略.....}
              }catch(Exception ex){....}
              finally
                {
                    try { if (command.Connection != null)command.Connection.Close(); }
                    catch (Exception) { }
                }
oracle在本地连接一直没有问题,后来因oracle太卡,所以弄了远程的服务器(无线路由)结果经常大约在3分钟左右不进行数据库操作的话,就会产生异常ORA-a03113: end-of-file on communication channel,  
注意:是异常,而不是重连造成的慢,实在是让人郁闷.
并且在刷新一到两次后则会成功连接,并可操作数据库