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问题是计算得出的 SumCustomerDebt。

我需要根据 CustomerLocation 进行分组，但 CustomerDebt 在表中重复多次（对于每个客户，具有不同的值）。我需要计算 SumCustomerDebt - 作为每个客户的 CustomerDebt 的总和。对于每个客户，CustomerDebt 是 CustomerDebt 的平均值。

我该怎么做？

这是我的 C# 代码。

protected DataTable generateData()
{
    DataTable dt = new DataTable();
    DataColumn column1 = new DataColumn("salesId", Type.GetType("System.Int32"));
    dt.Columns.Add(column1);
    DataColumn column2 = new DataColumn("CustomerLocation", Type.GetType("System.String"));
    dt.Columns.Add(column2);
    DataColumn column3 = new DataColumn("CustomerID", Type.GetType("System.Int32"));
    dt.Columns.Add(column3);
    DataColumn column4 = new DataColumn("CustomerDebt", Type.GetType("System.Int32"));
    dt.Columns.Add(column4);
    DataColumn column5 = new DataColumn("SubTotal", Type.GetType("System.Int32"));
    dt.Columns.Add(column5);


    DataRow dr = dt.NewRow();
    dr["salesId"] = 1;
    dr["CustomerLocation"] = "Chichago";
    dr["CustomerID"] = 1;
    dr["CustomerDebt"] = 100;
    dr["SubTotal"] = 10;
    dt.Rows.Add(dr);

    dr = dt.NewRow();
    dr["salesId"] = 2;
    dr["CustomerLocation"] = "Chichago";
    dr["CustomerID"] = 1;
    dr["CustomerDebt"] = 80;
    dr["SubTotal"] = 40;
    dt.Rows.Add(dr);

    dr = dt.NewRow();
    dr["salesId"] = 3;
    dr["CustomerLocation"] = "Chichago";
    dr["CustomerID"] = 2;
    dr["CustomerDebt"] = 50;
    dr["SubTotal"] = 30;
    dt.Rows.Add(dr);

    dr = dt.NewRow();
    dr["salesId"] = 4;
    dr["CustomerLocation"] = "Miami";
    dr["CustomerID"] = 3;
    dr["CustomerDebt"] = 20;
    dr["SubTotal"] = 50;
    dt.Rows.Add(dr);

    return dt;

}

protected void test()
{
    DataTable dt = generateData();

    var result = from row in dt.AsEnumerable()
                  group row by new
                  {
                      CustomerLocation = row.Field<string>("CustomerLocation"),
                  } into grp
                  select new
                  {
                      CustomerLocation = grp.Key.CustomerLocation,
                      SumSubTotal = grp.Sum(r => r.Field<int>("SubTotal")),
                      OrderCount = grp.Count(),
                      SumCustomerDebt = grp.Sum(r => r.Field<int>("CustomerDebt")),  //this is incorrect, how can i calculate it?
                  };


    foreach (var item in result)
    {
        string info = string.Format("CustomerLocation={0},SumSubTotal={1},OrderCount={2},SumCustomerDebt={3}", item.CustomerLocation, item.SumSubTotal, item.OrderCount, item.SumCustomerDebt);
        Console.WriteLine(info);

    }

}

打印的信息应包含 2 行：
1) "CustomerLocation=Chichago,SumSubTotal=80,OrderCount=3, SumCustomerDebt=150" -> SumCustomerDebt 等于 140 = 90（对于 CustomerID=1 (100+80)/2 平均值）+ 50 （对于 CustomerID=2）
2) "CustomerLocation=Miami,SumSubTotal=50,OrderCount=1, SumCustomerDebt=20"

4

1 回答 1

0 
protected void test()
{
    DataTable dt = generateData();

    var result = from row in dt.AsEnumerable()
                  group row by new
                  {
                      CustomerLocation = row.Field<string>("CustomerLocation"),
                  } into grp
                  select new
                  {
                      CustomerLocation = grp.Key.CustomerLocation,
                      SumSubTotal = grp.Sum(r => r.Field<int>("SubTotal")),
                      OrderCount = grp.Count(),
                      SumCustomerDebt = grp.GroupBy(r=> r.Field<int>("CustomerID"))
                                           .Sum(g => g.Average(r=> r.Field<int>("CustomerDebt"))),
                  };


    foreach (var item in result)
    {
        string info = string.Format("CustomerLocation={0},SumSubTotal={1},OrderCount={2},SumCustomerDebt={3}", item.CustomerLocation, item.SumSubTotal, item.OrderCount, item.SumCustomerDebt);
        Console.WriteLine(info);    
    }
}

这是输出

CustomerLocation=Chichago,SumSubTotal=80,OrderCount=3,SumCustomerDebt=140
CustomerLocation=Miami,SumSubTotal=50,OrderCount=1,SumCustomerDebt=20
于 2013-11-10T08:57:54.813 回答