Question

我想枚举Linq查询。下面是我指定的例子。

EX：

 DataTable _slidingDataTable = new DataTable("test");

 for(int i=0; i<5;i++)
 {
  DataRow row = _slidingDataTable.NewRow();

   startPosition = DateTime.Now;
   for(int i=0; i<5;i++)
   {
      _slidingDataTable.Columns.Add("TransferTime");
       row[columnName] = startPosition ;
       _slidingDataTable.Columns.Add("TransferData");
       row[columnName] = "Test"+i;
    }

 _slidingDataTable.Rows.Add(row);
 }


 var query1 = from myRow in _slidingDataTable.AsEnumerable()
                        where myRow.Field<DateTime>("TransferTime") == startPosition
                        select myRow;

此查询输出应为行集合。如何获得收集行＆amp;迭代。

Answer 1

在您的上下文中，query1是EnumerableRowCollection<DataRow>因为您使用了_slidingDataTable.AsEnumerable()，您可以像这样迭代它：

foreach (DataRow row in query1)
{ 
    // Do stuff with that row
}

Answer 2

我给你一个例子，你可以看到它，它还包括groupby中的总和。

var drdatedisp = from row in dtfullreport.AsEnumerable()
                             group row by row.Field<string>("Order_Date") into g
                             select new
                             {
                                 Order_Date = g.Key,
                                 totalQnty = g.Sum(a => a.Field<int>("Item_Quantity")),
                                 totalTax = g.Sum(a => float.Parse(a.Field<decimal>("TAXAMT").ToString())),
                                 totalAmt = g.Sum(a => float.Parse(a.Field<decimal>("VALAMT").ToString()))
                             };
            DataTable dtdatedisp = new DataTable();
            dtdatedisp.Columns.Add("Order_Date");
            dtdatedisp.Columns.Add("Item_Quantity");
            dtdatedisp.Columns.Add("TAXAMT");
            dtdatedisp.Columns.Add("VALAMT");
            dtdatedisp.Rows.Clear();
            foreach (var g in drdatedisp)
            {
                DataRow newRow1 = dtdatedisp.NewRow();
                newRow1[0] = g.Order_Date;
                newRow1[1] = g.totalQnty;
                newRow1[2] = String.Format("{0:0.00}", g.totalTax);
                newRow1[3] = String.Format("{0:0.00}", g.totalAmt);
                dtdatedisp.Rows.Add(newRow1);
            }

DataTable linq查询迭代

2 个答案: