Как выбрать элементы ListBox несколько раз, используя vb.net

Question

У меня есть форма окна с 2 выпадающими списками и списком. Каждый из них отображает элементы в зависимости от того, что выбрано в каждом.

Для списка, множественный выбор включен и работает, но я хочу иметь возможность разрешить выбор элементов в списке несколько раз. Разрешение пользователю выбирать один и тот же элемент / элементы несколько раз, если это имеет смысл.

Я использую VS2015

Вот мой текущий код:

    Imports System.Data
    Imports System.Configuration
    Imports System.Data.SqlClient

   Public Class MainHome

Dim con As SqlConnection = New SqlConnection("Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=\\Galactic\TSC_TIME_MATRIX$\DEV\TMX.mdf;Integrated Security=True")
'Dim constr As String
Dim querystring As String


' "Please Select" doesn't work well in the ListBox, I added it as an option
Private Shared Function GetData(ByVal sql As String, insertPleaseSelect As Boolean) As DataTable
    Dim constr As String = "Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=\\Galactic\TSC_TIME_MATRIX$\DEV\TMX.mdf;Integrated Security=True"
    Using con As SqlConnection = New SqlConnection(constr)
        Using sda As SqlDataAdapter = New SqlDataAdapter(sql, con)
            Dim dt As DataTable = New DataTable()
            sda.Fill(dt)
            If insertPleaseSelect Then
                Dim row As DataRow = dt.NewRow()
                row(0) = 1
                row(1) = "Please Select"
                dt.Rows.InsertAt(row, 0)
            End If
            Return dt
        End Using
    End Using
End Function

Private Sub MainHome_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
    ComboBox1.DataSource = GetData("SELECT  [SizeId], [SizeName] FROM [Size]", True)
    ComboBox1.DisplayMember = "SizeName"
    ComboBox1.ValueMember = "SizeId"
    ComboBox2.Enabled = False
    ListBox1.SelectionMode = SelectionMode.MultiSimple ' allow multi-select
End Sub

Private Sub ComboBox1_SelectionChangeCommitted(sender As Object, e As EventArgs) Handles ComboBox1.SelectionChangeCommitted
    ComboBox2.DataSource = Nothing
    ComboBox2.Enabled = False
    If ComboBox1.SelectedValue.ToString() <> "0" Then
        Dim sql As String = String.Format("SELECT [DetailLevelId], [DetailLevelName] FROM [DetailLevel] WHERE [SizeId] = {0}", ComboBox1.SelectedValue)
        ComboBox2.DataSource = GetData(sql, True)
        ComboBox2.DisplayMember = "DetailLevelName"
        ComboBox2.ValueMember = "DetailLevelId"
        ComboBox2.Enabled = True
    End If
End Sub

Private Sub ComboBox2_SelectionChangeCommitted(sender As Object, e As EventArgs) Handles ComboBox2.SelectionChangeCommitted
    ListBox1.DataSource = Nothing
    ListBox1.Enabled = False
    If ComboBox2.SelectedValue.ToString() <> "0" Then
        Dim sql As String = String.Format("SELECT [OperationsId], [OperationsName], [OperationsTime] FROM [Operations] WHERE [DetailLevelId] = {0}", ComboBox2.SelectedValue)
        ListBox1.DataSource = GetData(sql, False)
        ListBox1.DisplayMember = "OperationsName" ' changed this from ValueMember to DisplayMember
        ListBox1.ValueMember = "OperationsTime"
        ListBox1.Enabled = True
        ListBox1.ClearSelected() ' Every time the ListBox is populated, clear it
    End If
End Sub

' Added this handler to respond to user input, not programmatic selection changes
Private Sub ListBox1_Click(sender As Object, e As EventArgs) Handles ListBox1.Click
    ' Here is the sum

    'TotalMinutes
    Dim TotalMinutes = ListBox1.SelectedItems.OfType(Of DataRowView).Sum(Function(o) CType(o("OperationsTime"), Double))
    lbTotalMins.Text = TotalMinutes


    'Total Hours
    Dim TotalHours = ListBox1.SelectedItems.OfType(Of DataRowView).Sum(Function(o) CType(o("OperationsTime"), Double)) / 60.0
    lbTotalHours.Text = Format(TotalHours, "0.00")

    'Total Days
    Dim TotalDays = ListBox1.SelectedItems.OfType(Of DataRowView).Sum(Function(o) CType(o("OperationsTime"), Double)) / 1440.0
    lbTotalDays.Text = Format(TotalDays, "0.0")


    'Oven TIme
    Dim CureOvenSum = ListBox1.SelectedItems.OfType(Of DataRowView).Where(Function(o) o("OperationsName").ToString() = "CURE/OVEN").Sum(Function(o) CType(o("OperationsTime"), Double)) / 60

    Dim postCureOvenSum = ListBox1.SelectedItems.OfType(Of DataRowView).Where(Function(o) o("OperationsName").ToString() = "POST CURE/OVEN").Sum(Function(o) CType(o("OperationsTime"), Double)) / 60
    lbTotalOven.Text = Format(postCureOvenSum + CureOvenSum, "0.00")

End Sub

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    'Using sda As SqlDataAdapter = New SqlDataAdapter(sql, con)

    ' Dim constr As String
    ' Dim con As SqlConnection = New SqlConnection("Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\hartj\Documents\visual studio 2015\Projects\TIMEMATRIX2.0\TIMEMATRIX2.0\TMX.mdf;Integrated Security=True")
    Try
        con.Open()

        querystring = "INSERT INTO ArchiveData(DATE,PART_NUMBER,JOB_NUMBER,REV,IMS_DATE,ASSEMBLY_SIZE,DETAIL_LEVEL,OPERATIONS,USER_NAME,TOTAL_TIME,TOTAL_HOURS,TOTAL_DAYS,TOTAL_OVEN,NOTES)VALUES(' " & MainStart.tbDateToday.Text & " ',' " & tbPartNum.Text & " ',' " & tbJobNum.Text & " ',' " & tbRev.Text & " ',' " & tbIMS.Text & " ',' " & ComboBox1.Text & " ',' " & ComboBox2.Text & " ',' " & ListBox1.Text & " ',' " & MainStart.tbUserName.Text & " ',' " & lbTotalMins.Text & " ',' " & lbTotalHours.Text & " ',' " & lbTotalDays.Text & " ',' " & lbTotalOven.Text & " ',' " & rtbNOTES.Text & " ')"

        Dim Comm As SqlCommand = New SqlCommand(querystring, con)

        Comm.ExecuteNonQuery()
        MsgBox("Data Succesfully Saved!", MsgBoxStyle.Information, "add")

    Catch ex As Exception
        MessageBox.Show(ex.Message)

        con.Close()

    End Try
End Sub

Заранее спасибо!