动态产生Grid的column

DeptColumn.cs
using System;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Diagnostics;
namespace Asus.WebSite.QBR.SurveyTemplate
{
    
    public class DeptColumn :TemplateColumn
    {
        public DeptColumn(string dept)
        {
            this.HeaderText = dept;
            HeaderStyle.HorizontalAlign = HorizontalAlign.Center;
            HeaderStyle.Width = Unit.Percentage(9);
            ItemStyle.CssClass = "Normal";
            ItemTemplate = new IDeptColumn(dept);
        }
    }

    public class IDeptColumn:ITemplate
    {

        ReturnData _dbAccess = null;
        private string _dept = string.Empty;
        
        public IDeptColumn(string dept)
        {
            _dept = dept;
            _dbAccess = new ReturnData();
        }

        public void InstantiateIn(System.Web.UI.Control container)
        {
            DropDownList dl = new DropDownList();
            dl.CssClass = "Normal";
            dl.Width = Unit.Pixel(100);
            dl.ID = "dl_" + _dept;
            dl.DataBinding += new EventHandler(dl_OnDataBinding);
               
            container.Controls.Add(dl);    
        }
    
        private void dl_OnDataBinding(object sender,EventArgs e)
        {
            DropDownList dl = (DropDownList)sender;
            DataGridItem container = (DataGridItem) dl.NamingContainer;
            string  qbrId = ((DataRowView)container.DataItem)["qbrId"].ToString();
            
            if (qbrId.Length > 0)
            {
                dl.DataSource = _dbAccess.QBR_SurveyPlanUserGet(int.Parse(qbrId),  _dept);
                dl.DataTextField = "username";
                dl.DataValueField = "userid";
            }    
            
        }

    }
}