GriedView中的列索引号是从1开始的，而行的索引是从0开始的，本来以为列的索引也是0开始，就这点小误区让我搞了好一会才找到问题的根点．以下是详细代码


public partial class tw2 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            this.createdb();

        }
    }
    private void createdb()
    {
        SqlConnection cn = new SqlConnection("server=.;database=zhang;uid=sa;pwd=410"); //(Data Source =服务器;Initial Catalog=数据库;Integrated Security=True")本地用户登录
        SqlDataAdapter adp = new SqlDataAdapter();
        adp.SelectCommand = new SqlCommand("select * from chang", cn);
        DataSet ds = new DataSet();
        adp.Fill(ds, "chang");
        this.GridView1.DataKeyNames = new string[] { "changid" }; //定义主键
        this.GridView1.DataSource = ds.Tables[0].DefaultView;
        this.GridView1.DataBind();
        cn.Close();

    }
    protected void GridView1_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e) //取消按钮
    {
        GridView1.EditIndex = -1;
        this.createdb();
    }
    protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e) //编辑按钮
    {
        GridView1.EditIndex = e.NewEditIndex;
        this.createdb();
    }
    protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e) //选择按钮
    {
       int id = Convert.ToInt32(e.CommandArgument); //取行索引号
       string txt = GridView1.DataKeys[id].Value.ToString();　//取主键的值
       Response.Write(txt);
       // this.createdb();
      
    }
    protected void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e) //删除按钮
    {
        SqlConnection cn = new SqlConnection("server=.;database=zhang;uid=sa;pwd=410");
        cn.Open();
        SqlCommand cm=new SqlCommand("delete from chang where changid=" +GridView1.DataKeys[e.RowIndex].Value,cn); //e.RowIndex取本行索引号，
        cm.ExecuteNonQuery();
        cn.Close();
        GridView1.EditIndex = -1;
        this.createdb();
      
    }
    protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e) //更新按钮
    {
        GridViewRow   row   =   GridView1.Rows[e.RowIndex];
        TextBox   box   =   (TextBox)row.Cells[2].Controls[0];
        Response.Write(box.Text);
        try
        {
            SqlConnection cn = new SqlConnection("server=.;database=zhang;uid=sa;pwd=410");
            cn.Open();
            SqlCommand cm = new SqlCommand("update chang set chang1='" + ((TextBox)(GridView1.Rows[e.RowIndex].Cells[2].Controls[0])).Text.ToString().Trim() + "',chang2='" + ((TextBox)(GridView1.Rows[e.RowIndex].Cells[3].Controls[0])).Text.ToString().Trim() + "' where changid=" + GridView1.DataKeys[e.RowIndex].Value, cn); //列的编号是从1,这里更新的是第二列和第三列所以cell[2],cell[3],而行的索引是从0开始的
            cm.ExecuteNonQuery();
            GridView1.EditIndex = -1;
            this.createdb();
            cn.Close();
        }
        catch (Exception exc)
        {
            Response.Write(exc.Message);
        }
    }
  
}