protected void GridPlan_RowUpdating(object sender, GridViewUpdateEventArgs e)
        {
            ssc = new SqlServerClass();
            for (int i = 0; i <= GridPlan.Rows.Count - 1; i++)
            {
                TextBox TextBox1 = ((TextBox)GridPlan.Rows[e.RowIndex].FindControl("TextBox1"));
                string prm = TextBox1.Text;
                string sql = "UPDATE DO_TtxtMng SET valtext='"+prm +"' where Id_rec=16"; 
                ssc.UpdateALL(sql);
            }
 

 <EditItemTemplate>
 <asp:TextBox ID="TextBox1" runat="server" Text='<%# Bind("valtext") %>' 
  AutoPostBack="False"></asp:TextBox></EditItemTemplate>