我正在尝试在vb.net中创建下一个按钮来浏览我的访问数据库

Question

问题是，无论我从哪个位置开始，每次按下时它都从第一个记录开始，然后正确地向前移动，而我希望它从我所在的位置开始。我真的是编程新手，已经为此苦苦挣扎了两天了：(这是该表格的代码

Imports System.Data.OleDb
Imports System.IO

Public Class Details
    Private Sub ShowData(CurrentRow)
        Try
            TbxSName.Text = Dst.Tables("Mushrooms").Rows(CurrentRow)("Scientific_Name")
            TbxCName.Text = Dst.Tables("Mushrooms").Rows(CurrentRow)("Common_Name")
            TbxDescription.Text = Dst.Tables("Mushrooms").Rows(CurrentRow)("Description")
            TbxEdibilty.Text = Dst.Tables("Mushrooms").Rows(CurrentRow)("Edibility")
            TbxLocation.Text = Dst.Tables("Mushrooms").Rows(CurrentRow)("Location")
            TbxMorphology.Text = Dst.Tables("Mushrooms").Rows(CurrentRow)("Morphology")
        Catch ex As Exception
            MsgBox(ex.Message, "error")
        End Try
    End Sub
    Sub clr()
        TbxSName.Clear()
        TbxCName.Clear()
        TbxDescription.Clear()
        TbxEdibilty.Clear()
        TbxLocation.Clear()
        TbxMorphology.Clear()
    End Sub

    Private Sub Details_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Call connection()

        Currentrow = 0

        Dad = New OleDbDataAdapter("SELECT * FROM Mushrooms", cn)

        Dad.Fill(Dst, "Mushrooms")
        ShowData(Currentrow)



    End Sub

    Private Sub BtnNext_Click(sender As Object, e As EventArgs) Handles BtnNext.Click
        Call connection()

        If Currentrow = Dst.Tables("Mushrooms").Rows.Count - 1 Then
            MsgBox("Last Record is Reached", MsgBoxStyle.Exclamation)
        Else
            Currentrow += 1
                ShowData(Currentrow)
            End If

        cn.Close()

    End Sub


End Class

Answer 1

不要从某个地方呼叫连接。在使用它的地方创建它。连接需要关闭和处理。即使出现错误，使用块也可以为您完成此操作。在显示的代码中，您似乎不需要DataAdapter或DataSet。只需使用数据表和命令即可。

由于您尚未共享声明Currentrow的位置或方式，因此我无法告诉您为什么它没有更新。另外，您还没有共享ShowData方法，所以我无法确定那里是否出了问题。

Private conString As String = "Your connection string"
Private CurrentRow As Integer
Private dt As DataTable

Private Sub Details_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    dt = New DataTable
    Using cn As New OleDbConnection(conString),
            cmd As New OleDbCommand("SELECT * FROM Mushrooms", cn)
        dt.Load(cmd.ExecuteReader)
    End Using
    CurrentRow = 0
    ShowData()
End Sub

Private Sub BtnNext_Click(sender As Object, e As EventArgs) Handles BtnNext.Click
    If CurrentRow >= dt.Rows.Count - 1 Then
        MessageBox.Show("Last Record is Reached")
    Else
        CurrentRow += 1
        ShowData()
    End If
End Sub

Private Sub ShowData()
    TbxSName.Text = dt.Rows(CurrentRow)("Scientific_Name").ToString
    TbxCName.Text = dt.Rows(CurrentRow)("Common_Name").ToString
    TbxDescription.Text = dt.Rows(CurrentRow)("Description").ToString
    TbxEdibilty.Text = dt.Rows(CurrentRow)("Edibility").ToString
    TbxLocation.Text = dt.Rows(CurrentRow)("Location").ToString
    TbxMorphology.Text = dt.Rows(CurrentRow)("Morphology").ToString
End Sub