计算数据库表某一列的和

        public double consumeTotal(DataSet myDs)
        {
            int i = 0;
            double sumMoney = 0;
            int myCount = myDs.Tables[0].Rows.Count;  //行数
            for (i = 0; i < myCount; i++)
            {
            sumMoney += double.Parse(myDs.Tables[0].Rows[i]["消费金额"].ToString()); //每一行的“消费金额”这一列的值
            }
            return sumMoney;
        }