dynamically generated textboxes

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C#

ASP.NET

Hello

I have generated textboxes dynamically in a panel in my web form. I was also able to empty them by panel1.controls.clear()
bt this did not resolved my problem.

Explanation:
when page loads, on clicking first button 2 textbox appear in the panel and then again on click of that button 2 more appear. now we have 4 textbox. if we enter data into it and click on 2nd button the data is inserted into database and controls inside panel gets clear with "panel1.controls.clear();".
now if we click on first button again.. it gives 6 textboxes whereas i should get 2 textbox.

aspx.cs code

List<TextBox> textboxes = new List<TextBox>();
    protected void Page_Load(object sender, EventArgs e)
    {
            for (int i = 0; i < TotalNumberAdded; ++i)
            {
                AddControls(i + 1);
            }
            Button1.Click += new EventHandler(Button1_Click);
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        TotalNumberAdded++;
        AddControls(TotalNumberAdded);
    }
    private void AddControls(int controlNumber)
    {
        var newTextbox = new TextBox();
        newTextbox.ID = "TextBox_" + controlNumber;
        textboxes.Add(newTextBox);
        Panel1.Controls.Add(newTextbox);
    }
    protected int TotalNumberAdded
    {
        get { return (int)(ViewState["TotalNumberAdded"] ?? 0); }
        set { ViewState["TotalNumberAdded"] = value; }
    }
    protected void Button2_Click(object sender, EventArgs e)
    {
        string connStr = ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString;
        SqlConnection conn = new SqlConnection();
        conn.ConnectionString = connStr;
        conn.Open();
        foreach (TextBox tb in textboxes)
        {
            if (tb.Text != "")
            {
                SqlCommand cmd = new SqlCommand("insert into place(city,area) values('"+TextBox1.Text+"','" + tb.Text + "')", conn);
                cmd.ExecuteNonQuery();
            }
        }
        conn.Close();
        TextBox1.Text = "";
        Panel1.Controls.Clear();
    }

I am new to asp.net so all the code for generating textbox dynamically was searched from internet. Let me know if i can improve my existing code with a better coding. :)

Please Help!! Thank you.