DataView可以帮我们直接获取Distinct数据，

DataTable dataTable;DataView dataView = dataTable.DefaultView;

DataTable dataTableDistinct = dataView.ToTable(true,"FieldName1","FieldName2","...");

//注：其中ToTable（）的第一个参数为是否DISTINCT

DataTable MyTable = ds.Tables[2]; //ds为数据集

DataTable dtClone = MyTable.Clone();  //创建新表
DataView dv = new DataView(dtClone);  //用于查找
dv.Sort = "Item";
foreach(DataRow dr in MyTable.Rows)   //单循环, 效率高一点
{
  int rowIndex = dv.FindRow(dr["Item"]);
  if (rowIndex == -1)
  {
    dtClone.ImportRow(dr);  //添加行
    dtClone.Rows[dtClone.Rows - 1]
["Quantity"] = (decimal)MyTable.Compute("Sum(Quantity)", string.Format("Item = '{0}'", dr["Item"].ToString());
//合计
  }
}
dtClone.AcceptChanges();

ds.Tables.Remove(MyTable); //删除旧表
ds.Tables.Add(dtClone); //添加新表

dtClone.Rows[dtClone.Rows.Count - 1] ["Quantity"] = (decimal)MyTable.Compute("Sum(Quantity)", string.Format("Item = '{0}'", dr["Item"].ToString()); //合计

巴特西

原来DataTable的Distinct竟如此简单!

DataView可以帮我们直接获取Distinct数据，

DataTable dataTable;DataView dataView = dataTable.DefaultView;

DataTable dataTableDistinct = dataView.ToTable(true,"FieldName1","FieldName2","...");

//注：其中ToTable（）的第一个参数为是否DISTINCT

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