Question

我有一个像这样的列表：

如何检查此列表中是否存在值？ listaProduktow是一个列表

Private Function PobierzProduktyKategorii(ByVal nazwaSklepu As String, ByVal idSklepKategorie As Integer) As List(Of Object)
        Dim sql As String = "SELECT Id_sklep_kategorie, Id_rodzic FROM SKLEP_KATEGORIE WHERE Usunieto = 0 AND Id_rodzic = @IdSklepKategorie ORDER BY Kolejnosc ASC"
        Dim produkty As List(Of Object) = New List(Of Object)

        Polacz(nazwaSklepu)

        Dim sqlCommand As New MySqlCommand
        With sqlCommand
            .Connection = connection
            .CommandText = sql
            .Parameters.AddWithValue("@IdSklepKategorie", idSklepKategorie)
        End With

        Try
            Using dr As MySqlDataReader = sqlCommand.ExecuteReader()
                If dr.HasRows Then
                    While dr.Read
                        produkty.Add(PobierzProduktyKategorii(nazwaSklepu, dr("Id_sklep_kategorie")))
                    End While
                Else
                    Rozlacz()
                    Polacz(nazwaSklepu)
                    Dim sql2 As String = "SELECT Id_produkty FROM PRODUKTY WHERE Blokada = 0 AND Usunieto = 0 AND Id_sklep_kategorie = @IdSklepKategorie"
                    Dim sqlCommand2 As New MySqlCommand
                    With sqlCommand2
                        .Connection = connection
                        .CommandText = sql2
                        .Parameters.AddWithValue("@IdSklepKategorie", idSklepKategorie)
                    End With
                    Using dr2 As MySqlDataReader = sqlCommand2.ExecuteReader()
                        While dr2.Read
                            produkty.Add(dr2("Id_produkty"))
                        End While
                    End Using
                End If
            End Using
        Catch ex As MySqlException
            Logi.LogInfo(ex)
        Catch ex As Exception
            Logi.LogInfo(ex)
        Finally
            Rozlacz()
        End Try


        Return produkty
    End Function

Produkty也是一个List，您可以在代码顶部看到。我通过这样做来递归地添加值：produkty.add（myFunction（）），并且这个函数返回一个Object数组，这就是为什么。

Answer 1

您可以使用(ls file* | select -Expand Basename) -join ' - '和Enumerable.Cast<uint>：

Enumerable.Contains

所以你改用VB.NET。您还有一个多维数组的uint[,] array2D = new uint[,] { { 1, 2 }, { 3, 4 }, { 5, 6 }, { 7, 8 } }; uint value = 6; bool valueExists = array2D.Cast<uint>().Contains(value); // true instread。

您应使用List(Of List(Of Object))而不是Object，而不是Int32而不是dr2.GetInt32("Id_produkty")。然后你得到一个dr2("Id_produkty")：

List(Of List(Of Int32))

现在，您可以使用Private Function PobierzProduktyKategorii(ByVal nazwaSklepu As String, ByVal idSklepKategorie As Integer) As List(Of List(Of Int32)) Dim produkty As New List(Of List(Of Int32)) ' .... ' Using dr2 As MySqlDataReader = sqlCommand2.ExecuteReader() While dr2.Read produkty.Add(dr2.GetInt32("Id_produkty")) End While End Using ' ... ' If dr.HasRows Then While dr.Read produkty.Add(PobierzProduktyKategorii(nazwaSklepu, dr("Id_sklep_kategorie"))) End While Else ' ... ' Dim subList As New List(Of Int32) Using dr2 As MySqlDataReader = sqlCommand2.ExecuteReader() While dr2.Read subList.Add(dr2.GetInt32("Id_produkty")) End While End Using produkty.Add(subList) ' a single list added ' End If ' ... ' return produkty End Function + SelectMany

搜索这些列表

Contains

检查多维List <of object =“”>（列表中的列表）中是否存在值

1 个答案: