Inserting values into and from database using dynamic controls

protected void btnadd_Click(object sender, EventArgs e)
    {
        this.AddControl(this.DynamicControlCounter, this.DynamicControlCounter.ToString());

        this.DynamicControlCounter++;
        if (PlaceHolder1.Controls.Count > 0)
        {
            for (int i = 0; i < this.DynamicControlCounter; i++)
            {
                DropDownList ddlcity = (DropDownList)FindControl("dynamicddl_" + i);
                ddlcity.DataSource = ds;
                ddlcity.DataTextField = "city";
                ddlcity.DataBind();
            }
        }
    }




 protected void btnsave_Click(object sender, EventArgs e)
    {
        adpt= new SqlDataAdapter("insert into tab_name values('" + TextBox1.Text + "','" + DropDownList1.SelectedItem.ToString() + "')", con);
        adpt.Fill(ds);
        if (PlaceHolder1.Controls.Count > 0)
        {
            for (int i = 0; i < DynamicControlCounter; i++)
            {
                TextBox txtname = (TextBox)FindControl("dynamictext_" + i);
                DropDownList ddlcity = (DropDownList)FindControl("dynamicddl_"+i);
                adpt = new SqlDataAdapter("insert into tab_name values('" + txtname.Text + "','" + ddlcity.SelectedItem.ToString() + "')", con);
                adpt.Fill(ds);
            }
        }
    }