这应该让您入门

This should get you started

using(SqlConnection conn = new SqlConnection(...))
{
  using(SqlCommand cmd = new SqlCommand("SELECT ID, Name FROM Group", conn))
  {
    DataReader dr = cmd.ExecuteReader();
    while(dr.Read())
    {
       Button btn = new Button();
       btn.Text = dr["Name"].ToString();
       btn.CommandArgument = dr["ID"].ToString();
       btn.Command += new CommandEventHandler(OnBtnCommand);
       Controls.Add(btn);
    }
  }
}

protected void OnBtnCommand(object sender, CommandEventArgs e)
{
   // Load dropdown based on 
   int ID = int.Parse(e.CommandArgument);
}