Vb.net 从数据库创建和填充标签

目前，我正在开发一个用户可以输入和查看评论的系统。输入部分工作正常，但是让它显示注释不起作用

我目前试图做的是，对于comments表中的每个条目，我希望系统创建一个新标签，然后用日期、用户名和用户注释填充该标签的文本

我已经附上下面的代码，任何输入或指导都将不胜感激

Try
    Dim con As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Data\IMData.mdb;")
    Dim cmd As New OleDbCommand
    con.Open()
    cmd.Connection = con
    cmd.CommandText = "Select * from Comments where ID=@p1"
    cmd.Prepare()
    cmd.Parameters.AddWithValue("@p1", TrackNum.Text)
    Dim Comments = cmd.ExecuteReader
    Dim labelY = 418
    With Comments
        .Read()
        For Each item In Comments
            Dim newComment As New Label
            newComment.Name = item
            newComment.Left = 983
            newComment.Top = labelY
            newComment.Font = Font
            newComment.Text = .Item("Date") + " " + .Item("User") + " : " + .Item("Comment")
            newComment.Visible = True
            Me.Controls.Add(newComment)
            labelY += 47
        Next
        .Close()
    End With
    con.Close()
Catch
End Try

这是工作代码：

    Try
        Dim con As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Data\IMData.mdb;")
        Dim cmd As New OleDbCommand
        con.Open()
        cmd.Connection = con
        cmd.CommandText = "Select * from Comments where ID=@p1"
        cmd.Prepare()
        cmd.Parameters.AddWithValue("@p1", TrackNum.Text)
        Dim Comments = cmd.ExecuteReader
        With Comments
            .Read()
            Dim labelY = 418
            For Each item In Comments
                Dim newComment As New Label
                newComment.Name = labelY
                newComment.Top = labelY
                labelY += 47
                newComment.Left = 983
                newComment.Font = Font
                newComment.Text = item("Date") + " : " + item("User") + " : " + item("Comment")
                newComment.Width = 900
                newComment.Visible = True
                Me.Controls.Add(newComment)
            Next
            .Close()
        End With
        con.Close()
    Catch ex As Exception
        MsgBox(ex.ToString)
    End Try

---

这里有几个错误，因为它是在一个try，catch上没有输出，所以您没有看到问题

有关更正，请参见下面的注释：

Try
    Dim con As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Data\IMData.mdb;")
    Dim cmd As New OleDbCommand
    con.Open()
    cmd.Connection = con
    cmd.CommandText = "Select * from Comments where ID=@p1"
    cmd.Prepare()
    cmd.Parameters.AddWithValue("@p1", TrackNum.Text)
    Dim Comments = cmd.ExecuteReader
    Dim labelY = 418
    With Comments
        .Read()
        For Each item In Comments
            Dim newComment As New Label
            newComment.Name = item 'this needs to be a string such as item("ID") - must be unique!'
            newComment.Left = 983
            newComment.Top = labelY
            newComment.Font = Font
            newComment.Text = .Item("Date") + " " + .Item("User") + " : " + .Item("Comment")
                              'these 'Item's should not have the period in front of them'
            newComment.Visible = True
            Me.Controls.Add(newComment)
            labelY += 47
        Next
        .Close()
    End With
    con.Close()
Catch
'add in something to catch the error such as console.writeline'
End Try

---

不幸的是，我仍然无法让它工作。。。我已将.Name=item（“ID”）更改为labelY（因此它是唯一的，所有ID都是相同的），并删除了句点，但我无法让它仍然工作。我想捕获注释捕获的内容，以查看ExecuteReader获得的内容，但我也不知道如何使其正常工作……如果在捕获（同一行）后添加

ex As Exception

，则可以使用console.writeline（ex.tostring）或（等待反对意见…）msgbox（ex.tostring），它将向您显示错误的位置或位置（等待爆炸…）对于调试注释，请尝试，共捕获！感谢OSKM！我得到的错误是System.InvalidCastException:从字符串“Wo311110414”转换键入“Double”无效。System.FormatException:输入字符串的格式不正确。它是否指示了错误发生在哪一行？顺便说一句，如果ID为uniqueManaged以使其正常工作，则更为正常。需要定义.Width？我将在一分钟内用工作代码编辑上面的内容。