Save checked ASP.Net CheckBox value in Database using C#

Dear @ukd,

 please modify your submitquestion click event like below,

protected void Submitquestion_Click(object sender, EventArgs e)
{
 
    string chkbox1Value="";
	string chkbox2Value="";
	string chkbox3Value="";
	
     if(checkbox1.Checked)
        {
         chkbox1Value="True";
        }
        else
        {
        chkbox1Value="False";
        }

        if(checkbox2.Checked)
        {
			chkbox2Value="True";
        }
        else
        {
        chkbox2Value="False";
        }
 
        if(checkbox3.Checked)
        {
        chkbox3Value="True";
        }
        else
        {
        chkbox3Value="False";
        }

       string chkboxLevel=chkbox1Value+","+chkbox2Value+","+chkbox3Value;



        obj.CreateConnectionsql();
         string query = "insert into Question(Question , Answer, Chapter_name, Question_type_id,Level ) values('" + txtquestion.Text + "','" + txtanswer.Text + "','" + ddlchaptername.SelectedIndex + "','" + ddlquestionlevel.SelectedIndex + "','" + chkboxLevel + "')";
         SqlCommand cmd = new SqlCommand(query, clsDataAccess.Conn);
         cmd.ExecuteNonQuery();
         txtquestion.Text = string.Empty;
         txtanswer.Text = string.Empty;
         checkbox1.Text = string.Empty;
         checkbox2.Text = string.Empty;
         checkbox3.Text = string.Empty;
         obj.CloseConnection();
}