Web Forms :: Save (Insert) Value (Text) Of Dynamic TextBox In MasterPage To Database

My Code to be fired During Button 

protected void Button2_Click(object sender, EventArgs e) {
foreach (Control ctl in Dynamic.Controls) {
if (ctl is TextBox) {
TextBox tb = (TextBox)ctl;
using (SqlConnection con = new SqlConnection(_connStr)) {

[Code] .....

 PlaceHolder
<asp:PlaceHolder ID="Dynamic" runat="server">
</asp:PlaceHolder>

I am not able to find the TextBox inside Placeholder. The Ids are also randomly Generated. I debugged it but the code comes out of foreach loop .