尝试更新表时发生并发冲突

Question

我需要帮助来更新我的数据网格上的数据。当我更改“ Kode”的值并单击“编辑”按钮时，它运行良好，但是当我更改“ Kode_Kategori_Kamar”或“状态”的值时，出现错误消息：

  

“并发违反update命令影响了预期的1条记录中的0条。”

我正在使用Visual Studio 2017和XAMPP（MySQL）。我尝试重新排列代码，删除WHERE子句，并使用try...catch。

Imports MySql.Data.MySqlClient
Public Class frmKamar
Public hostconn As New MySqlConnection
Sub enable()
    txtKode.Enabled = True
    cmbKategori.Enabled = True
    cmbStatus.Enabled = True
End Sub

Sub disable()
    txtKode.Enabled = False
    cmbKategori.Enabled = False
    cmbStatus.Enabled = False
End Sub

Sub bersih()
    txtKode.Clear()
    cmbKategori.SelectedItem = Nothing
    cmbStatus.SelectedItem = Nothing
End Sub

Public Sub frmKamar_Disposed(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Disposed
    frmMenu.Show()
    dst.Tables.Clear()
    conn.Close()
End Sub

Private Sub frmKamar_Shown(sender As Object, e As EventArgs) Handles Me.Shown
    If (ConnectionState.Closed) Then
        conn.Open()
    End If
End Sub

Private Sub frmKamar_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    connect("localhost", "root", "", "dbhotel")
    Try
        da = New MySqlDataAdapter("select * from kamar", conn)
        da.Fill(dst, "kamar")
        dgKamar.DataSource = dst.Tables("kamar")
        dgKamar.CaptionText = "Data ke. " & dgKamar.CurrentRowIndex + 1 & " of " & dst.Tables("kamar").Rows.Count()
    Catch myerror As MySqlException
        MessageBox.Show("Error connecting to Database : " & myerror.Message)
    End Try
    cmbStatus.Items.Add("Terisi")
    cmbStatus.Items.Add("Kosong")
    combobx()
    disable()
End Sub

Sub combobx()
    Try
        Dim cd = New MySqlCommand("select * from kategori_kamar", conn)
        rd = cd.ExecuteReader()
        While rd.Read()
            Me.cmbKategori.Items.Add(rd("kode"))
        End While
        rd.close()
    Catch ex As Exception
        MessageBox.Show("Koneksi Gagal ! : " & ex.Message)
    End Try
End Sub
Dim state As StateEnum
Private Enum StateEnum
    StateIdle = 0
    StateNew = 1
    StateEdit = 2
End Enum

Private Sub btnBaru_Click(sender As Object, e As EventArgs) Handles btnBaru.Click
    enable()
    state = StateEnum.StateNew
End Sub

Private Sub btnSimpan_Click(sender As Object, e As EventArgs) Handles btnSimpan.Click
    Select Case state
        Case Is = StateEnum.StateNew
            Dim databaru As DataRow = dst.Tables("kamar").NewRow
            Try
                databaru("kode") = txtKode.Text
                databaru("kode_kategori_kamar") = cmbKategori.SelectedItem
                databaru("status") = cmbStatus.SelectedItem
                dst.Tables("kamar").Rows.Add(databaru)
                MsgBox("Data berhasil ditambahkan", MsgBoxStyle.Information)
                bersih()
            Catch err As Exception
                MsgBox(err.Message, MsgBoxStyle.Exclamation, "error")
                dst = New DataSet
                da = New MySqlDataAdapter("select * from kamar", conn)
                da.Fill(dst, "kamar")
                dgKamar.DataSource = dst.Tables("kamar")
                Exit Sub
            End Try
        Case Is = StateEnum.StateEdit
            Dim myEditRow As DataRow = dst.Tables("kamar").Rows(dgKamar.CurrentRowIndex)
            Try
                myEditRow("kode") = txtKode.Text
                myEditRow("kode_kategori_kamar") = cmbKategori.SelectedItem
                myEditRow("status") = cmbStatus.SelectedItem
                Dim Sql As String
                Sql = "UPDATE kamar SET kode = '" & txtKode.Text & "', kode_kategori_kamar = '" & cmbKategori.SelectedItem &
                    "', status = '" & cmbStatus.SelectedItem & "' where kode = '" & txtKode.Text & "'"
                Dim cmd = New MySqlCommand(Sql, conn)
                cmd.ExecuteNonQuery()
                myEditRow.BeginEdit()
                MsgBox("Data berhasil diupdate", MsgBoxStyle.Information)
                dgKamar.Enabled = True
            Catch ex As Exception
                MsgBox(ex.Message, MsgBoxStyle.Exclamation, "error")
                dst = New DataSet
                da = New MySqlDataAdapter("select * from kamar", conn)
                da.Fill(dst, "kamar")
                dgKamar.DataSource = dst.Tables("kamar")
                Exit Sub
            End Try
    End Select
    Dim datacomm As New MySqlCommandBuilder(da)
    da.Update(dst, "kamar")
    bersih()
    disable()
End Sub

Private Sub btnEdit_Click(sender As Object, e As EventArgs) Handles btnEdit.Click
    state = StateEnum.StateEdit
    Me.BindingContext(dst.Tables("kamar")).Position = dgKamar.CurrentRowIndex()
    txtKode.DataBindings.Add("text", dst.Tables("kamar"), "kode")
    cmbKategori.DataBindings.Add("text", dst.Tables("kamar"), "kode_kategori_kamar")
    cmbStatus.DataBindings.Add("text", dst.Tables("kamar"), "status")
    Dim ctrl As Control
    For Each ctrl In GroupBox1.Controls
        ctrl.DataBindings.Clear()
    Next ctrl
    dgKamar.Enabled = False
    enable()
End Sub

Private Sub btnHapus_Click(sender As Object, e As EventArgs) Handles btnHapus.Click
    dst.Tables("kamar").Rows(dgKamar.CurrentRowIndex).Delete()
    Dim datacomm As New MySqlCommandBuilder(da)
    da.Update(dst, "kamar")
End Sub

Private Sub btnBatal_Click(sender As Object, e As EventArgs) Handles btnBatal.Click
    dgKamar.Enabled = True
    bersih()
    disable()
End Sub

Private Sub btnKeluar_Click(sender As Object, e As EventArgs) Handles btnKeluar.Click
    Close()
End Sub
End Class