DataBinding:“System.String”不包含名为“TotalType”的属性。
筛选不重复类型作为数据源：
public List<string> GetTotallType()
    {
        SqlConnection conn =
           new SqlConnection("data source=localhost;initial catalog=Supermarket;uid=sa;pwd=123456;");

        conn.Open();
        SqlCommand cmd = new SqlCommand();
        cmd.Connection = conn;
        cmd.CommandText = "Select TotalType from GoodsTypeList";
        SqlDataReader reader = cmd.ExecuteReader();

        List<string> list = new List<string>();
        while (reader.Read())
        {
            bool isTrue = false;
            for (int i = 0; i < list.Count; i++)
            {
                if (reader["TotalType"].ToString() == list[i])
                {
                    isTrue = true;
                    break;
                }
            }
            if (isTrue == false)
            {
                list.Add(reader["TotalType"].ToString());
            }
        }
        return list;

    }

 protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)