Linq VB.NET - vb.net、linq、linq-to-sqlを使用してグループ内の最大日付項目を選択

示されているようなデータがあります。

NameA Date
NameA Date
NameA Date
NameB Date
NameB Date
NameC Date
NameD Date
NameD Date

最新の日付のレコードのみを取得して、以下のように返してもらいたいと思います。以下で始めたLinqの構文について混乱していますが、どこに行くのかわかりません。

NameA Date
NameB Date
NameC Date
NameD Date

Linqを開始しました

Dim pciLST = _
From p As SmartFormData(Of PCISF) In pciSFM.GetList(m_Criteria) _
Where p.SmartForm.EmployeeUsername.ToLower() = m_Username.ToLower() AndAlso _
IsOpen(p.SmartForm.CompletedDate, p.SmartForm.ActiveFor, p.SmartForm.Open)

回答

Dim pciLST = _
From g In pciSFM.GetList(m_Criteria).AsEnumerable() _
Where g.SmartForm.EmployeeUsername.ToLower() = m_Username.ToLower() _
Order By (g.SmartForm.CompletedDate) Descending _
Take 1 _
Select _
Name = IIf(g.SmartForm.FormName Is Nothing, "", g.SmartForm.FormName.ToString()), _
DateSigned = IIf(g.SmartForm.CompletedDate IsNot Nothing AndAlso _
Date.TryParse(g.SmartForm.CompletedDate, New Date()), g.SmartForm.CompletedDate, New Date(1, 1, 1)), _
ActiveFor = IIf(g.SmartForm.ActiveFor Is Nothing, -1, Integer.Parse(g.SmartForm.ActiveFor)), _
NewLink = IIf(g.SmartForm.NewLink Is Nothing, "", g.SmartForm.NewLink.ToString()), _
ViewLink = IIf(g.SmartForm.ViewLink Is Nothing, "", g.SmartForm.ViewLink.ToString()), _
Open = IIf(g.SmartForm.Open Is Nothing, -1, Integer.Parse(g.SmartForm.Open)), _
Requirement = IIf(g.SmartForm.Requirement Is Nothing, "", g.SmartForm.Requirement.ToString()), _
Archived = Boolean.Parse(g.SmartForm.Archived), _
Id = Long.Parse(g.Content.Id), _
Due = GetDue(Date.Parse(g.SmartForm.CompletedDate), Integer.Parse(g.SmartForm.ActiveFor))

Return pciLST.AsQueryable()

回答：

このコードは現在機能しています

public class NameDate
Public Name As String
Public D As DateTime
End Class
. . . . .
Dim list As New List(Of NameDate)(4)
list.Add(New NameDate() With {.Name = "A", .D = DateTime.Now.AddDays(-10)})
list.Add(New NameDate() With {.Name = "A", .D = DateTime.Now})
list.Add(New NameDate() With {.Name = "B", .D = DateTime.Now.AddDays(-10)})
list.Add(New NameDate() With {.Name = "B", .D = DateTime.Now.AddDays(-20)})

Dim o = From nd In list _
Group nd By nd.Name Into g = Group _
Select New NameDate() With {.Name = g.First().Name, .D = g.Max(Function(x) x.D)}

o.ToList().ForEach(Sub(x) Debug.WriteLine(x.Name & " - - " & x.D.ToString()))

これがオリジナルのc＃です

var o = from nd in list
group nd by nd.Name
into g
select new NameDate() {Name = g.Key, Date = g.Max(d => d.Date)};