来自 Vb.Net 数据表的不同行

Question

我有一个场景，我必须在 DataTable 上应用不同的过滤器，然后只找到不同的行， 我使用dt.DefaultView.ToTable(True, Columns)这个语句但是没有效果。

这是我的代码块..

Try
        Dim dTable As New DataTable()
        dTable.Columns.Add("AutoID")
        dTable.Columns.Add("AnotherID")
        dTable.Columns.Add("CitY")
        Dim row As DataRow = Nothing
        For i As Integer = 0 To 4
            row = dTable.NewRow()
            row("AutoID") = i + 1
            row("AnotherID") = i + 10
            row("City") = "Vetican"
            dTable.Rows.Add(row)
        Next
        dTable.Rows.Add(6, "11", "Oslo")
        dTable.Rows.Add(7, "12", "Toronto")

        Dim TobeDistinct As String() = {"AnotherID"}
        Dim dtDistinct As DataTable = GetDistinctRecords(dTable, TobeDistinct)

    Catch ex As Exception

    End Try

还有方法..

Public Shared Function GetDistinctRecords(ByVal dt As DataTable, ByVal Columns As String()) As DataTable
    Dim dtURecords As New DataTable()
    dtURecords = dt.DefaultView.ToTable(True, Columns)
    Return dtURecords
End Function

这是我想要的屏幕截图..

Answer 1

您要保留哪些行以及应该删除哪些行？如果您只想为每个AnotherID 保留一行，那么保留Vetican 而不是Oslo 似乎是任意的。也许您想像Vetican, Oslo 一样连接两者。

我会改用Linq：

Dim resultTable = dTable.Clone() ' empty table same columns
Dim idGroups = dTable.AsEnumerable().GroupBy(Function(r) r.Field(Of String)("AnotherID"))
For Each grp In idGroups
    Dim r As DataRow = resultTable.Rows.Add()
    r.SetField("AutoID", grp.First().Field(Of String)("AutoID"))
    r.SetField("AnotherID", grp.Key)
    Dim cities = From row In grp Select row.Field(Of String)("City")
    r.SetField("City", String.Join(", ", cities))
Next