Vb.net 试图从本地DataTable将ListBox所选项目的总和获取到标签中_Vb.net_Winforms_Visual Studio 2015

Vb.net 试图从本地DataTable将ListBox所选项目的总和获取到标签中

vb.net winforms visual-studio-2015

Vb.net 试图从本地DataTable将ListBox所选项目的总和获取到标签中,vb.net,winforms,visual-studio-2015,Vb.net,Winforms,Visual Studio 2015,我已经搜索了好几天，寻找任何可能的参考或建议，但我遇到的一切都没有起作用目标： Imports System.Data Imports System.Configuration Imports System.Data.SqlClient Public Class MainHome Private Function GetData(ByVal sql As String) As DataTable Dim constr As String = "Data Source=

我已经搜索了好几天，寻找任何可能的参考或建议，但我遇到的一切都没有起作用

目标：

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

Public Class MainHome
    Private Function GetData(ByVal sql As String) As DataTable
        Dim constr As String = "Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\hartj\Documents\visual studio 2015\Projects\TIMEMATRIX2.0\TIMEMATRIX2.0\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)
                Dim row As DataRow = dt.NewRow()
                row(0) = 1
                row(1) = "Please Select"
                dt.Rows.InsertAt(row, 0)
                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 = Me.GetData("SELECT  SizeId, SizeName FROM Size")
        ComboBox1.DisplayMember = "SizeName"
        ComboBox1.ValueMember = "SizeId"
        ComboBox2.Enabled = False
        ComboBox3.Enabled = False
    End Sub

    Private Sub ComboBox1_SelectionChangeCommitted(sender As Object, e As EventArgs) Handles ComboBox1.SelectionChangeCommitted
        ComboBox2.DataSource = Nothing
        ComboBox3.DataSource = Nothing
        ComboBox2.Enabled = False
        ComboBox3.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 = Me.GetData(sql)
            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 = Me.GetData(sql)
            ListBox1.ValueMember = "OperationsName"
            ListBox1.ValueMember = "OperationsTime"
            ListBox1.Enabled = True

            Label9.Text = CType(ListBox1.SelectedValue, Integer).ToString
            'Label.Text = CType(cbbank.SelectedItem, DataRowView).Row.Item("Account").ToString
        End IF
    End Sub

用户将在ComboBox1中选择选项，然后确定Combox2中的可用选项，然后在ListBox1中填充操作列表

当用户在ListBox1中选择可用操作时，我需要将输出值（本例中的总时间，以分钟为单位）加在标签中以供显示

中使用的数据存储在本地数据库中。到目前为止，我的组合框和列表框都能正常工作

我正在尝试获取ListBox1中所有选定项目的文本值，以将我表格中的数值（第4列“操作时间”）输出到一个标签中，该标签将显示所有选择的总和（总时间（分钟）

我在其他帖子中尝试过的一些东西：

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

Public Class MainHome
    Private Function GetData(ByVal sql As String) As DataTable
        Dim constr As String = "Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\hartj\Documents\visual studio 2015\Projects\TIMEMATRIX2.0\TIMEMATRIX2.0\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)
                Dim row As DataRow = dt.NewRow()
                row(0) = 1
                row(1) = "Please Select"
                dt.Rows.InsertAt(row, 0)
                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 = Me.GetData("SELECT  SizeId, SizeName FROM Size")
        ComboBox1.DisplayMember = "SizeName"
        ComboBox1.ValueMember = "SizeId"
        ComboBox2.Enabled = False
        ComboBox3.Enabled = False
    End Sub

    Private Sub ComboBox1_SelectionChangeCommitted(sender As Object, e As EventArgs) Handles ComboBox1.SelectionChangeCommitted
        ComboBox2.DataSource = Nothing
        ComboBox3.DataSource = Nothing
        ComboBox2.Enabled = False
        ComboBox3.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 = Me.GetData(sql)
            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 = Me.GetData(sql)
            ListBox1.ValueMember = "OperationsName"
            ListBox1.ValueMember = "OperationsTime"
            ListBox1.Enabled = True

            Label9.Text = CType(ListBox1.SelectedValue, Integer).ToString
            'Label.Text = CType(cbbank.SelectedItem, DataRowView).Row.Item("Account").ToString
        End IF
    End Sub

尝试使用双精度：

         Dim Total As Double = 0
    For Each Time As Integer In ListBox1.SelectedItems
        Total += CDbl(Time.ToString.Substring(Time.ToString.LastIndexOf(",") + 1))
    Next
    Label9.Text = Total.ToString

表格的屏幕截图：

下面是我的代码：

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

Public Class MainHome
    Private Function GetData(ByVal sql As String) As DataTable
        Dim constr As String = "Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\hartj\Documents\visual studio 2015\Projects\TIMEMATRIX2.0\TIMEMATRIX2.0\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)
                Dim row As DataRow = dt.NewRow()
                row(0) = 1
                row(1) = "Please Select"
                dt.Rows.InsertAt(row, 0)
                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 = Me.GetData("SELECT  SizeId, SizeName FROM Size")
        ComboBox1.DisplayMember = "SizeName"
        ComboBox1.ValueMember = "SizeId"
        ComboBox2.Enabled = False
        ComboBox3.Enabled = False
    End Sub

    Private Sub ComboBox1_SelectionChangeCommitted(sender As Object, e As EventArgs) Handles ComboBox1.SelectionChangeCommitted
        ComboBox2.DataSource = Nothing
        ComboBox3.DataSource = Nothing
        ComboBox2.Enabled = False
        ComboBox3.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 = Me.GetData(sql)
            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 = Me.GetData(sql)
            ListBox1.ValueMember = "OperationsName"
            ListBox1.ValueMember = "OperationsTime"
            ListBox1.Enabled = True

            Label9.Text = CType(ListBox1.SelectedValue, Integer).ToString
            'Label.Text = CType(cbbank.SelectedItem, DataRowView).Row.Item("Account").ToString
        End IF
    End Sub

导入系统数据
导入系统配置
导入System.Data.SqlClient
公营家庭
私有函数GetData（ByVal sql作为字符串）作为DataTable
Dim constr As String=“数据源=（LocalDB）\MSSQLLocalDB；AttachDbFilename=C:\Users\hartj\Documents\visualstudio 2015\Projects\TIMEMATRIX2.0\TIMEMATRIX2.0\TMX.mdf；集成安全性=True”
使用con作为SqlConnection=newsqlconnection（cont）
将sda用作SqlDataAdapter=新的SqlDataAdapter（sql，con）
作为数据表的Dim dt=新数据表（）
sda.填充（dt）
作为DataRow=dt.NewRow（）的Dim行
行（0）=1
第（1）行=“请选择”
dt.行插入符（行，0）
返回dt
终端使用
终端使用
端函数
Private Sub MainHome_Load（发送方作为System.Object，e作为System.EventArgs）处理MyBase.Load
ComboBox1.DataSource=Me.GetData（“从大小中选择SizeId、SizeName”）
ComboBox1.DisplayMember=“SizeName”
ComboBox1.ValueMember=“SizeId”
ComboBox2.Enabled=False
ComboBox3.Enabled=False
端接头
私有子Combox1\u SelectionChangeCommitted（发送方作为对象，e作为事件参数）处理Combox1.SelectionChangeCommitted
ComboBox2.DataSource=无
ComboBox3.DataSource=无
ComboBox2.Enabled=False
ComboBox3.Enabled=False
如果ComboBox1.SelectedValue.ToString（）为“0”，则
Dim sql As String=String.Format（“从DetailLevel中选择DetailLevelId，DetailLevelName，其中SizeId={0}”，ComboBox1.SelectedValue）
ComboBox2.DataSource=Me.GetData（sql）
ComboBox2.DisplayMember=“DetailLevelName”
ComboBox2.ValueMember=“DetailLevelId”
ComboBox2.Enabled=True
如果结束
端接头
私有子Combox2\u SelectionChangeCommitted（发送方作为对象，e作为事件参数）处理Combox2.SelectionChangeCommitted
ListBox1.DataSource=无
ListBox1.Enabled=False
如果ComboBox2.SelectedValue.ToString（）为“0”，则
Dim sql As String=String.Format（“从DetailLevelId={0}的操作中选择OperationsId、OperationsName、OperationsTime”，ComboBox2.SelectedValue）
ListBox1.DataSource=Me.GetData（sql）
ListBox1.ValueMember=“操作名称”
ListBox1.ValueMember=“操作时间”
ListBox1.Enabled=True
Label9.Text=CType（ListBox1.SelectedValue，整数）.ToString
'Label.Text=CType（cbbank.SelectedItem，DataRowView）.Row.Item（“帐户”）.ToString
如果结束
端接头

无需从

数据行视图

获取

数据行

，因为您可以直接从

数据行视图

访问字段值。它可以并且确实做了许多与

DataRow

相同的事情

这是最传统的方式，但也有其他选择。你可以向它扔点大麻：

Dim totalOperationsTime = ListBox1.SelectedItems.Cast(Of DataRowView)().
                                                 Sum(Function(view) CDbl(view("OperationsTime")))

有点恼人的是，

ValueMember

属性只帮助您获取

SelectedItem

的值。这是我不久前编写的一个类，它添加了一个

GetItemValue

方法，该方法使用

ValueMember

的功能与

GetItemText

方法对

DisplayMember

的功能一样：

Public Class ListBoxEx
    Inherits ListBox

    Public Function GetItemValue(item As Object) As Object
        Dim index = Me.Items.IndexOf(item)

        If (index <> -1 AndAlso Me.DataManager IsNot Nothing) Then
            Return Me.FilterItemOnProperty(Me.DataManager.List(index), Me.ValueMember)
        End If

        Return Nothing
    End Function

End Class

或者这个：

Dim totalOperationsTime = ListBox1.SelectedItems.Cast(Of Object)().
                                                 Sum(Function(item) CDbl(ListBoxEx1.GetItemValue(item)))

使用该自定义控件的一个优点是，您不必知道数据源或其项的类型。您只需知道

ValueMember

已设置。

我对您的代码做了一些更改。它与列表框一起工作。有关详细信息，请参见注释

' "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=C:\Users\hartj\Documents\visual studio 2015\Projects\TIMEMATRIX2.0\TIMEMATRIX2.0\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
    Label9.Text = ListBox1.SelectedItems.OfType(Of DataRowView).Sum(Function(o) CType(o("OperationsTime"), Double))
End Sub

““请选择”在列表框中不起作用，我将其作为选项添加
私有共享函数GetData（ByVal sql作为字符串，insertPleaseSelect作为布尔值）作为DataTable
Dim constr As String=“数据源=（LocalDB）\MSSQLLocalDB；AttachDbFilename=C:\Users\hartj\Documents\visualstudio 2015\Projects\TIMEMATRIX2.0\TIMEMATRIX2.0\TMX.mdf；集成安全性=True”
使用con作为SqlConnection=newsqlconnection（cont）
将sda用作SqlDataAdapter=新的SqlDataAdapter（sql，con）
作为数据表的Dim dt=新数据表（）
sda.填充（dt）
如果插入，请选择，然后
作为DataRow=dt.NewRow（）的Dim行
行（0）=1
第（1）行=“请选择”
dt.行插入符（行，0）
如果结束
返回dt
终端使用
终端使用
端函数
Private Sub MainHome_Load（发送方作为System.Object，e作为System.EventArgs）处理MyBase.Load
ComboBox1.DataSource=GetData（“从[Size]中选择[SizeId]，[SizeName]，True）
ComboBox1.DisplayMember=“SizeName”
ComboBox1.ValueMember=“SizeId”
ComboBox2.Enabled=False
列表框1.Selecti
Dim totalOperationsTime As Double

For Each item In ListBoxEx1.SelectedItems
    totalOperationsTime += CDbl(ListBoxEx1.GetItemValue(item))
Next

Dim totalOperationsTime = ListBox1.SelectedItems.Cast(Of Object)().
                                                 Sum(Function(item) CDbl(ListBoxEx1.GetItemValue(item)))

' "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=C:\Users\hartj\Documents\visual studio 2015\Projects\TIMEMATRIX2.0\TIMEMATRIX2.0\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
    Label9.Text = ListBox1.SelectedItems.OfType(Of DataRowView).Sum(Function(o) CType(o("OperationsTime"), Double))
End Sub