Dynamic templatefield in gridview

protected void Button2_Click(object sender, EventArgs e)
    {
        loadDynamicGridWithTemplateColumn();
    }
 
    private void loadDynamicGridWithTemplateColumn()
    {
        #region Code for preparing the DataTable
 
        //Create an instance of DataTable
        DataTable dt = new DataTable();
 

 

 
        sqlconn = new SqlConnection(connstring);
        string sql = "SELECT ROW_NUMBER() OVER(ORDER BY ssm.stu_name) AS 'row_num', stu_name, pk_student_id FROM SM_STUDENT_MASTER ssm WHERE ssm.current_class = '" + select_class.SelectedValue.ToString() + "' AND ssm.current_section = '" + select_section.SelectedValue.ToString() + "' AND ssm.stu_status <> 0 ORDER BY stu_name";
        sqlconn.Open();
        SqlDataAdapter da = new SqlDataAdapter(sql, sqlconn);
        DataSet ds = new DataSet();
        da.Fill(dt);
        GridView1.DataSource = ds.Tables[0];
        GridView1.DataBind();
        sqlconn.Close();
 

 

//This is the dynamic portion which will be given by the user..

        //Create an Pronunciation column for adding to the Datatable
        DataColumn dcol = new DataColumn(Pronunciation, typeof(System.String));
        dt.Columns.Add(dcol);
 
        //Create an Fluency column for adding to the Datatable
        dcol = new DataColumn(Fluency, typeof(System.String));
        dt.Columns.Add(dcol);
 
        //Create an Comprehension column for adding to the Datatable
        dcol = new DataColumn(Comprehension, typeof(System.String));
        dt.Columns.Add(dcol);
 
        //Create an Overall column for adding to the Datatable
        dcol = new DataColumn(Overall, typeof(System.String));
        dt.Columns.Add(dcol);
 
        //Now add data for dynamic columns
        //As the first column is auto-increment, we do not have to add any thing.
        //Let's add some data to the second column.
        for (int nIndex = 0; nIndex < 10; nIndex++)
        {
            ////Create a new row
            //DataRow drow = dt.NewRow();

            ////Initialize the row data.
            //drow[Pronunciation] = "";
            //drow[Fluency] = "";
            //drow[Comprehension] = "";
            //drow[Overall] = "";

            ////Add the row to the datatable.
            //dt.Rows.Add(drow);
        }
        #endregion
 
        //Iterate through the columns of the datatable to set the data bound field dynamically.
        //foreach (DataColumn col in dt.Columns)
        
        for (int i = 0; i <= dt.Columns.Count; i++)
        {
            if (i < 7)
            {
                DataColumn col1 = dt.Columns[i];
                
                //Declare the bound field and allocate memory for the bound field.
                TemplateField bfield = new TemplateField();
 
                //Initalize the DataField value.
                bfield.HeaderTemplate = new GridViewTemplate(ListItemType.Header, col1.ColumnName);
 
                //Initialize the HeaderText field value.
                bfield.ItemTemplate = new GridViewTemplate(ListItemType.Item, col1.ColumnName);
 
                //Add the newly created bound field to the GridView.
                
                //if (dt.Columns.Count < 7)
                {
                    GridView1.Columns.Add(bfield);
                }               
            }
            
        }
 
        //dt.Columns.Remove("row_num");

        //Initialize the DataSource
        GridView1.DataSource = dt;
        //Bind the datatable with the GridView.
        GridView1.DataBind();
        
        //for (int i = 0; i <= GridView1.Columns.Count; i++)
        //{ if (i < 6) GridView1.Columns.RemoveAt(i); }
    }