why the InvalidOperationException in foreach loop which prints contents of database

[Hawabi]

DataRow[] returnedrows = data.Tables["off"].Select("empid='" + employeeid + "'");
 
            count = returnedrows.Length;
            if (count > 0)
            {
                foreach(DataRow dr in Table_main.Rows)
                {
 
                    Console.WriteLine(dr["empid"] + "\t" + dr["empname"] + "\t" + dr["designation"]);
                    Console.WriteLine("select the operation you would like to perform");
                    Console.WriteLine("1.UPDATE INFORMATION \n2.DELETE EMPLOYEE INFORMATION \n3.EXIT\n");
                    int info_emp;
                    string info = Console.ReadLine();
                    int.TryParse(info, out info_emp);
 
 
                    switch (info_emp)
                    {
                        case 1:
 
                            Console.WriteLine(">>>>>>please enter the NEW DESIGNATION u want to update to<<<<<<<<");
                            string desg = Console.ReadLine();
                            cmd.CommandText = "UPDATE off SET designation='"+desg+"' WHERE empid='" + employeeid + "';";
                            cmd.ExecuteNonQuery();
 
                            cmd.CommandText = "select * from off where empid='" + employeeid + "'";
                            adap.SelectCommand = cmd;
                            adap.Fill(data, "off");
 
 
                             int.TryParse(id, out employeeid);
                            //adap.Update(data, "off");
                             trans.Commit();
 
 
                                foreach (DataRow myDataRow in data.Tables["off"].Rows)
                                     {
                                     Console.WriteLine("EMPLOYEEID = " + myDataRow["empid"] );
 
                                     Console.WriteLine("\tEMPLOYEEName = " + myDataRow["empname"]);
 
                                     Console.WriteLine("\tDESIGNATION = " + myDataRow["designation"]+"\n");
 
                                      }
                        break;
                        case 2:
                            cmd.CommandText = "delete from off where empid='" + employeeid + "';";
                            cmd.ExecuteNonQuery();
                            Console.WriteLine("DELETE SUCCESSFULLLLL");
                            trans.Commit();
                            break;
                        case 3:
                            Environment.Exit(0);
                            break;
                        default:
                            Console.WriteLine("Invalid selection");
                            break;
                    }
                }
 
            }
            else
            {
                char c;
                Console.WriteLine("SORRY...THE EMPLOYEE ID IS INCORRECT..do you want to add new employee?");
                string input= Console.ReadLine();
                char.TryParse(input, out c);
                while (c == 'y')
                {
                    Console.WriteLine("ENTER EMPLOYEE NAME :");
                    string employeename = Console.ReadLine();
                    Console.WriteLine("ENTER DESIGNATION :");
                    string employeedesg = Console.ReadLine();
 
 
 
                    cmd.CommandText = "insert into off (empid,empname, designation)" + " values " + "('" + employeeid + "',' " + employeename + "','" + employeedesg + " ')";;
                    cmd.ExecuteNonQuery();
                    Console.WriteLine("RECORD INSERTED SUCCESSFULLLY");
                    cmd.CommandText = "select * from off";
                    adap.SelectCommand = cmd;
                    adap.Fill(data, "off");
                    DataTable Table = data.Tables["off"];
                    foreach (DataRow myDataRow in Table.Rows)
                    {
                        Console.WriteLine("EMPLOYEEID = " + myDataRow["empid"]);
                        Console.WriteLine("\t");
                        Console.WriteLine("EMPLOYEEName = " + myDataRow["empname"]);
                        Console.WriteLine("\t");
                        Console.WriteLine("DESIGNATION = " + myDataRow["designation"]);
                        Console.WriteLine("\t");
 
                    }
                    break;
 
                }
                Console.WriteLine("press q to exit");
                input = Console.ReadLine();
                char.TryParse(input, out c);
                while (c == 'q')
                    Environment.Exit(0);
 
 
            }
 
 
            conn.Close();
 
            Console.ReadLine();
 
        }

[Hawabi]

How do i edit this for each loop??

[Rabbit]

Please use code tags when posting code.

Which line causes the error?