gridview动态生成模版列后，实现编辑更新的问题

我需要实现的结果是
根据设置，运行时在gridview中生成不同的模版列，绑定数据并在gridview中实现编辑删除。

在网上找了一些资料后。实现了部分效果
1、根据设置生成模版列并绑定数据实现了
方法：动态生成TemplateField并插入到gridview。代码如下：
（当处理GridView1_RowEditing的时候发现，如果我在load时加上了if (!IsPostBack)则点编辑后会在gridview增加
与现有列数目相同的空列，去掉if (!IsPostBack)后发现还是增加，于是加上GridView1.Columns.Clear();后暂时可以实现
点击编辑后显示textbox并绑定数据了。与此同时遇到另一个问题，修改数据后，点更新的时候，无法查询到修改后的数据。
还有一个问题：为什么我在load的时候Label l = (Label)GridView1.Rows[3].FindControl("label计算机");就能找到值而在GridView1_RowEditing如果加上if (!IsPostBack)则label l的值就时null呢？）
2、如何实现编辑更新？是不是我的方法错了？各位大大给点建议。谢谢

我问的有不清楚的地方请各位大大提出来呀。谢谢各位啦

    protected void Page_Load(object sender, EventArgs e)

    {

        //if (!IsPostBack)

        //{

            GridView1.Columns.Clear();

            tf4 = new TemplateField();

            tf4.ItemTemplate = new GridViewTemplate("Label", "计算机");

            tf4.EditItemTemplate = new GridViewTemplate("TextBox", "计算机");

            tf4.HeaderText = "计算机";

            GridView1.Columns.Add(tf4);

            tf4 = new TemplateField();

            tf4.ItemTemplate = new GridViewTemplate("Label", "数学");

            tf4.EditItemTemplate = new GridViewTemplate("TextBox", "数学");

            tf4.HeaderText = "数学";

            GridView1.Columns.Add(tf4);



            cf = new CommandField();

            cf.ShowDeleteButton = false;

            cf.ShowCancelButton = false;

            cf.ShowEditButton = true;

            GridView1.Columns.Add(cf);

            databind();

            Label l = (Label)GridView1.Rows[3].FindControl("label计算机");

            if (l != null) TextBox1.Text = "GridView1.Rows[3] label.text = " + l.Text;

            Label l2 = (Label)GridView1.Rows[3].FindControl("labeltext");

            if (l2 != null) TextBox2.Text = "GridView1.Rows[3] l2.text" + l2.Text;

        //}

    }

public class GridViewTemplate : ITemplate

{

    private string temptype;

    private string columnName;

    public GridViewTemplate(string type, string colname)

    {

        temptype = type;

        columnName = colname;

    }

    public void InstantiateIn(System.Web.UI.Control container)

    {

        switch (temptype.ToLower())

        {

            case "textbox":

                TextBox textbox = new TextBox();

                textbox.ID = "textbox" +columnName;

                textbox.Text = "test";

                //container.Controls.Add(textbox);

                textbox.DataBinding += new EventHandler(this.OnDataBinding);

                textbox.TextChanged += new EventHandler(this.OnTextChanged);

                container.Controls.Add(textbox);

                break;

            case "label":

                Label label = new Label();

                label.ID = "label" +columnName;

                //container.Controls.Add(label);

                label.DataBinding += new EventHandler(this.OnDataBinding);

                container.Controls.Add(label);

                break;

            default:

                break;

        }

    }

    private void OnTextChanged(object sender, EventArgs e)

    {

        ((TextBox)sender).Text += ":";

    }

    public void OnDataBinding(object sender, EventArgs e)

    {

        GridViewRow container;

        switch(temptype.ToLower())

        {

            case "label":

                Label l1 = (Label)sender;

                container = (GridViewRow)l1.NamingContainer;

                //l1.Text = ((DataRowView)container.DataItem)[columnName].ToString();

                l1.Text = DataBinder.Eval(container.DataItem, columnName).ToString();                                 

                break;

            case "textbox":

                TextBox l = (TextBox)sender;

                container = (GridViewRow)l.NamingContainer;

                //l.Text = ((DataRowView)container.DataItem)[columnName].ToString();

                l.Text = DataBinder.Eval(container.DataItem, columnName).ToString();

                break;

            default:

                break;

        }

    }

}

    protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)

    {

        Label l = (Label)GridView1.Rows[e.NewEditIndex].FindControl("label");

        TextBox lt = (TextBox)GridView1.Rows[e.NewEditIndex].FindControl("textbox计算机");

        if (l == null) TextBox1.Text = "l == null  is true;";

        if (l != null) TextBox1.Text = "l = " + l.Text;

        Label l3 = (Label)GridView1.Rows[e.NewEditIndex].FindControl("label数学");

        if (l3 != null) TextBox1.Text += "l3 = " + l3.Text;

        GridView1.EditIndex = e.NewEditIndex;

        databind();

    }

    ICollection CreateDataSource()

    {

        System.Data.DataTable dt = new System.Data.DataTable();

        System.Data.DataRow dr;

        dt.Columns.Add(new System.Data.DataColumn("学生班级", typeof(System.String)));

        dt.Columns.Add(new System.Data.DataColumn("学生姓名", typeof(System.String)));

        dt.Columns.Add(new System.Data.DataColumn("语文", typeof(System.Decimal)));

        dt.Columns.Add(new System.Data.DataColumn("数学", typeof(System.Decimal)));

        dt.Columns.Add(new System.Data.DataColumn("英语", typeof(System.Decimal)));

        dt.Columns.Add(new System.Data.DataColumn("计算机", typeof(System.Decimal)));



        for (int i = 0; i < 8; i++)

        {

            System.Random rd = new System.Random(Environment.TickCount * i); ;

            dr = dt.NewRow();

            dr[0] = "班级" + i.ToString();

            dr[1] = "学生" + i.ToString();

            dr[2] = System.Math.Round(rd.NextDouble() * 100, 2);

            dr[3] = System.Math.Round(rd.NextDouble() * 100, 2);

            dr[4] = System.Math.Round(rd.NextDouble() * 100, 2);

            dr[5] = System.Math.Round(rd.NextDouble() * 100, 2);

            dt.Rows.Add(dr);

        }

        System.Data.DataView dv = new System.Data.DataView(dt);

        return dv;

    }