如何基於特定的gridview列在gridview上創建虛擬列

Question

請讓我有一個項目，我使用實體框架查詢數據庫作爲我的ORM。這是我的查詢

Dim subjectSearch = From subSearch In DemoSchool.EssenceSubjectRegistrations Where subSearch.Session = drpSession.SelectedItem.Text _ 
       AndAlso subSearch.Term = drpTerm.SelectedItem.Text AndAlso subSearch.RealClass.ClassSN = findClassSN.FirstOrDefault AndAlso _ 
        subSearch.SubjectCode = drpSubject.SelectedValue _ 
        Select New With {.SubjectRegSN = subSearch.SubjectRegSN, 
            .FirstName = subSearch.Student.FirstName, 
            .Surname = subSearch.Student.Surname, 
            .CA1 = subSearch.CA1, 
            .CA2 = subSearch.CA2, 
            .CA3 = subSearch.CA3, 
            .CA4 = subSearch.CA4, 
            .CA5 = subSearch.CA5} 

然後我查詢我的結果，這樣我可以能夠通過這樣

Dim secSubjectSearch = (From jamie In subjectSearch Select jamie).ToList() _ 
         .Select(Function(jamie) New With {.SubjectRegSN = jamie.SubjectRegSN, 
         .FirstName = jamie.FirstName, 
         .Surname = jamie.Surname, 
         .CA1 = jamie.CA1, 
         .CA2 = jamie.CA2, 
         .CA3 = jamie.CA3, 
         .CA4 = jamie.CA4, 
         .CA5 = jamie.CA5, 
         .MidTerm = CDbl(jamie.CA1 + jamie.CA2 + jamie.CA3 + jamie.CA4 + jamie.CA5)/5}) 

第二查詢的結果做一些關於它的操作是有界到GridView哪些按原樣呈現正確渲染。我的問題是我想要在.MidTerm有界列之後的gridview上創建一個名爲Rank的虛擬列，它將在搜索結果中顯示每個人記錄的位置。

NAME  CA1  CA2  CA3 CA4  CA5 MIDTERM RANK 
    James  50  50  60  40  60  52  3 
    Essty  100  50  50  50  50  60  2 
    Markus  100  40  50  60  50  60  2 
    Code  100  100  100  100  50  90  1 

以上是gridview列的格式。我希望列的排名是一個虛擬的列，根據學生的中期分數計算。代碼VB得分90，所以他的排名等於1等。請我不知道如何計算這個排名列和代碼得到最高和最小。真的我需要幫助謝謝

Answer 1

兩種方式。

1. 使用綁定列和計算/顯示排名

2. 有一個RANK場和預先計算它，約束它，像：

    Dim secSubjectSearch = (From jamie In subjectSearch Select jamie).ToList() _ 
          .Select(Function(jamie) New With {.SubjectRegSN = jamie.SubjectRegSN, 
          .FirstName = jamie.FirstName, 
          .Surname = jamie.Surname, 
          .CA1 = jamie.CA1, 
          .CA2 = jamie.CA2, 
          .CA3 = jamie.CA3, 
          .CA4 = jamie.CA4, 
          .CA5 = jamie.CA5, 
          .MidTerm = CDbl(jamie.CA1 + jamie.CA2 + jamie.CA3 + jamie.CA4 + jamie.CA5)/5, 
          .RANK = -1}).ToList() 
        dim sorted = secSubjectSearch.Select(function(n) n.MidTerm).Distinct().OrderByDescending(function(n) n).ToList() 
        for each itm in secSubjectSearch 
         itm.RANK = sorted.IndexOf(itm.MidTerm) + 1 
        next 
   

- 不測試，用記事本寫它...