How to display multiple values to a column in database?

Question

 I have a different subject table and want to access multiple subjects name to subname attribute of exam_tbl through inserting student data . I want to insert data to tbl_exam on inserting to student table. 

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Drawing.Imaging;

using System.IO;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Windows.Forms;

using MySql.Data.MySqlClient;

namespace SISv2._0

{

public partial class AddStudent : Form

{

String regno = DBHandler.getGenerateNo();

public AddStudent()

{

InitializeComponent();

}

private void AddStudent_Load(object sender, EventArgs e)

{

loadData();

}

private void btn_Save_Click(object sender, EventArgs e)

{

InsertData();

}

private void btn_Reset_Click(object sender, EventArgs e)

{

ClearData();

}

private void btn_Exit_Click(object sender, EventArgs e)

{

this.Close();

}

private void btn_Browse_Click(object sender, EventArgs e)

{

PicBrowse();

}

private void InsertData()

{

if (txt_class.Text != "")

{

try

{

//------Image Making

Byte[] imageByte;

MemoryStream ms = new MemoryStream();

imageBox.Image.Save(ms, ImageFormat.Png);

imageByte = new Byte[ms.Length];

ms.Read(imageByte, 0, imageByte.Length);

ms.Close();

//------------------------->

DBHandler.OpenConnection();

string qry = "Insert into Student values ( '','" + regno + "','" + txt_sname.Text.Trim().ToString() + "','" + txt_class.Text.Trim().ToString() + "','" + txt_section.Text.Trim().ToString() + "','" + txt_roll.Text.Trim().ToString() + "','" + txt_fiscal.Text.Trim().ToString() + "','" + txt_saddress.Text.Trim().ToString() + "','" + txt_sdob.Text.Trim().ToString() + "','" + txt_pname.Text.Trim().ToString() + "','" + txt_occupation.Text.Trim().ToString() + "','" + txt_contact.Text.Trim().ToString() + "',@img)";

List<MySqlParameter> sqlParameter = new List<MySqlParameter>();

//imageparameter

sqlParameter.Add(new MySqlParameter() { MySqlDbType = MySqlDbType.Blob, ParameterName = "img", Value = imageByte });

//--------------Adding the parameter list

DBHandler.ExecuteQryNonQry(qry, sqlParameter);//Execute the non query Parameter

MessageBox.Show("Data Saved");

// DBHandler.CloseConnection();

}

catch (Exception ex)

{

MessageBox.Show(ex.ToString());

}

finally

{

DBHandler.CloseConnection();

ClearData();

loadData();

}

}

else

{

MessageBox.Show("Please insert full data correctly!!!");

}

// switchfunction(regno,txt_class.Text.ToString());

}

private void ClearData()

{

txt_sname.Clear();

txt_sid.Clear();

txt_saddress.Clear();

txt_class.SelectedIndex = -1;

txt_section.SelectedIndex = -1;

txt_roll.ResetText();

txt_pname.Clear();

txt_fiscal.SelectedIndex = -1;

txt_occupation.Clear();

txt_contact.Clear();

}

private void PicBrowse()

{

OpenFileDialog OF = new OpenFileDialog();

OF.Multiselect = false;

OF.Filter = "Image File |*.jpg;*.png;*.jpeg";

if (OF.ShowDialog() == System.Windows.Forms.DialogResult.OK)

{

imageBox.Image = Image.FromFile(OF.FileName);

}

}

private void loadData()

{

try

{

dataGridView1.Rows.Clear();

DBHandler.OpenConnection();

DBHandler.ExecuteQry("Select * from Student order by STDID asc", false);

MySqlDataReader sdr = DBHandler.sqlDataReader;

while (sdr.Read())

{

dataGridView1.Rows.Add(false, sdr[0], sdr[1], sdr[2], sdr[3], sdr[4], sdr[5], sdr[6], sdr[7], sdr[8], sdr[9], sdr[10], sdr[11]);

}

}

catch (Exception ex)

{

MessageBox.Show(ex.ToString());

}

finally

{

DBHandler.CloseConnection();

}

}

public void switchfunction()

{

try

{

// string test3 = test2;

int caseSwitch = Int32.Parse(txt_class.Text.ToString());

string s;

String current = DateTime.Now.ToString("dd-MM-yyyy");

switch (caseSwitch)

{

case 1:

{

String sclass = "1";

MySqlDataReader sdr = DBHandler.FetchData("Select * from subject where SUBCLASS ='" + sclass + "'");

while (sdr.Read())

{

s = (string)sdr["SUBNAME"];

MessageBox.Show(""+s);

} 

catch (MySqlException ex) {

MessageBox.Show(ex.Message);

}

}

}

}