您可以使用 LINQ to DataSets

You can use LINQ to DataSets

var sales = myDataSet.Tables["all_saled"].AsEnumerable();

var buy_total = sales.Sum(datarow => datarow.Field<int>("how_much_buy")); 

检查 LINQ to DataSets 101 示例

附言可能需要引用 System.Data.DataSetExtensions 程序集.

P.S. might need the System.Data.DataSetExtensions assembly referenced.