/// <summary>
    /// 返回购物袋所有商品的总额
    /// </summary>
    /// <returns></returns>
    public static string CommodityTotal()
    {
        SqlCommand comm = new SqlCommand("Select sum(总价) From 购物袋", conn);
        string sum = "0";
        conn.Open();
        if (comm.ExecuteNonQuery() != 0)
            sum = comm.ExecuteScalar().ToString();
        conn.Close();
        return sum;
    }

购物袋表里面并没有数据,为什么if语句却通过了?

明白了明白了!谢谢提醒!