在c＃中使用linq选择不在组中的更多列

Question

cmd = new SqlCommand(" ", con);

da = new SqlDataAdapter(cmd);
DataTable t_eight = new DataTable("t_eight");
da.Fill(t_eight); //databale "t_eight" fill

//linq query
var query3 = (from a in t_eight.AsEnumerable() //t_eigth Databale
              group a by new
              { //Group by with condition
                  IdendityName = a.Field<String>("Idendity Name"),
                  ContactPersonName = a.Field<String>("Contact Person Name"),
                  CustomerName = a.Field<String>("Customer Name")
              }
              into g
              select new
              {
                  IdendinyName = g.Key.IdendityName,
                  ContactPersonName = g.Key.ContactPersonName,
                  CurtomerName = g.Key.CustomerName,
                  TotalBook = g.Sum(x => x.Field<Int32>("Total Book Quantity")
                      + x.Field<Int32>("Quatan Book Qty")
                      - x.Field<Int32>("Return Book Quality"))
              });

GridView1.DataSource = query3;
GridView1.DataBind();

数据表包含“身份名称”，“客户名称”，“客户联系人姓名”，“总账簿数量”，“退货手册质量”和“Quatan手册数量”等列。

分组依据包含三列标识名称，客户名称和客户联系人姓名

select语句中的新列Total Book包含（书籍总量+ Quatan Book Qty-Return Book Quality）。我想要gridview中的所有列，但网格包含身份名称，客户名称，客户联系人姓名和总帐簿列

我该怎么做？

数据集表“t_eight”

Gridview缺少列Quatan Book和Return Book

Answer 1

假设您希望在对行进行分组后其他字段相同，您只需从组中选择一个随机行来获取值 - First行应该有效。

var query3 = (from a in t_eight.AsEnumerable()//t_eigth Databale

                      group a by new
                      {//Group by with condition
IdendityName = a.Field<String>("Idendity Name"),
ContactPersonName = a.Field<String>("Contact Person Name"),
CustomerName = a.Field<String>("Customer Name")
                      }
                          into g
                          select new {
                              g.Key.IdendityName,
                              g.Key.ContactPersonName,
                              g.Key.CustomerName,
                              ReturnBookQuality = g.First().Field<Int32>("Return Book Quality"),
                              QuatanBookQty = g.First().Field<Int32>("Quatan Book Qty"),
TotalBook = g.Sum(x => x.Field<Int32>("Total Book Quantity")
                                  + x.Field<Int32>("Quatan Book Qty") - x.Field<Int32>("Return Book Quality"))
                          }
              );

注意：我从匿名类型中删除了冗余的成员名称，我没有看到任何理由将它们放在那里。

Answer 2

如果我理解正确，您希望在计算的TotalBook列之外看到三列的总数。以下是您可以这样做的方法：

var query3 = (from a in t_eight.AsEnumerable()
              group a by new
              {
                  IdendityName = a.Field<String>("Idendity Name"),
                  ContactPersonName = a.Field<String>("Contact Person Name"),
                  CustomerName = a.Field<String>("Customer Name")
              }
              into g

              let tbq = g.Sum(x => x.Field<Int32>("Total Book Quantity"))
              let qbq = g.Sum(x => x.Field<Int32>("Quatan Book Qty"))
              let rbq = g.Sum(x => x.Field<Int32>("Return Book Quality"))

              select new
              {
                  IdendinyName = g.Key.IdendityName,
                  ContactPersonName = g.Key.ContactPersonName,
                  CurtomerName = g.Key.CustomerName,
                  TotalBookQuantity = tbq,
                  QuatanBookQuantity = qbq,
                  ReturnBookQuantity = rbq,
                  TotalBook = tbq + qbq - rbq
              });

三个let语句收集每个分组的各个总和，之后您可以多次使用变量tbq等。