How can I put a Sum() in this linq query?

Question

I am looking to sum the "Status" field.

    Dim _detailRecords As New DataTable
    _detailRecords.Columns.Add("y")
    _detailRecords.Columns.Add("z")
    _detailRecords.Columns.Add("A", GetType(Int32))

    Dim workRow As DataRow
    Dim i As Integer

    For i = 1 To 3
        workRow = _detailRecords.NewRow()
        workRow(0) = i.ToString()
        workRow(1) = "CustName" & i.ToString()
        workRow(2) = i + 1
        _detailRecords.Rows.Add(workRow)
    Next

    For i = 1 To 3
        workRow = _detailRecords.NewRow()
        workRow(0) = i.ToString()
        workRow(1) = "CustName" & i.ToString()
        workRow(2) = i + 1
        _detailRecords.Rows.Add(workRow)
    Next

Dim query8 As IEnumerable(Of DataRow) = (From record As DataRow In _detailRecords _
    Group record By y = record.Field(Of String)("y"), _
                   z = record.Field(Of String)("z"), _
                   Status = record.Field(Of Int32)("Status") Into groupedRecords = Group _
Select groupedRecords.FirstOrDefault())

I'm also wanting to keep this as an IEnumerable of DataRow because I will be creating a datatable from it with

Dim yyyyy As DataTable = query8.CopyToDataTable

Answer 1

Just add a call to the aggregate method you want and optionally add an alias to the result.

Dim query =
    From record In _detailRecords
    Group record
        By Y = record.Field(Of String)("y"),
           Z = record.Field(Of String)("z"),
           Status = record.Field(Of Int32)("Status")
        Into groupedRecords = Group,
             Sum(record.Field(Of Int32)("Status")) ' Get the sum of the Status values
    Select FirstRecord = groupedRecords.FirstOrDefault,
           Sum

Note that there are many ways this could be written, this is just one way.