using (var conn = new MySqlConnection('Connection String...'))
{
  conn.Open();
  //此处设置读取的超时，不然在海量数据时很容易超时
  var c = new MySqlCommand('set net_write_timeout=9999999; set net_read_timeout=9999999', conn);
  c.ExecuteNonQuery();

  MySqlCommand rcmd = new MySqlCommand();
  rcmd.Connection = conn;
  rcmd.CommandText = @'SELECT `f1`,`f2` FROM `table1`';
  //设置命令的执行超时
  rcmd.CommandTimeout = 99999999;
  var myData = rcmd.ExecuteReader();

  while (myData.Read())
  {
    var f1= myData.GetInt32(0);
    var f2= myData.GetString(1);
    //这里做数据处理....
  }
}

insert into table (f1,f2) values(1,'sss'),values(2,'bbbb'),values(3,'cccc');

 //使用StringBuilder高效拼接字符串
 var sqlBuilder = new StringBuilder();
 //添加insert 语句的头
 string sqlHeader = 'insert into table1 (`f1`,`f2`) values';
 sqlBuilder.Append(sqlHeader);
 using (var conn = new MySqlConnection('Connection String...'))
 {
   conn.Open();
   //此处设置读取的超时，不然在海量数据时很容易超时
   var c = new MySqlCommand('set net_write_timeout=9999999; set net_read_timeout=9999999', conn);
   c.ExecuteNonQuery();

   MySqlCommand rcmd = new MySqlCommand();
   rcmd.Connection = conn;
   rcmd.CommandText = @'SELECT `f1`,`f2` FROM `table1`';
   //设置命令的执行超时
   rcmd.CommandTimeout = 99999999;
   var myData = rcmd.ExecuteReader();
   while (myData.Read())
   {
     var f1 = myData.GetInt32(0);
     var f2 = myData.GetString(1);
     //这里做数据处理....
     sqlBuilder.AppendFormat('({0},'{1}'),', f1,AddSlash(f2));
     if (sqlBuilder.Length >= 1024 * 1024)//当然这里的1MB length的字符串并不等于 1MB的Packet。。。我知道：）
     {
       insertCmd.Execute(sqlBuilder.Remove(sqlBuilder.Length-1,1).ToString())//移除逗号，然后执行
       sqlBuilder.Clear();//清空
       sqlBuilder.Append(sqlHeader);//在加上insert 头
     }
   }
}