Question

我正在尝试使用datagridviews 创建一个包含所有代码的主 - 详细信息表单。 SELECT / fill部分工作正常，但我遇到UPDATE / INSERT / DELETE（当表单关闭时应自动发生）。以下代码给出了错误：

更新要求UpdateCommand具有连接对象。该 UpdateCommand的Connection属性尚未初始化。

在.Update行上

。

我尝试将连接移出GetData（）程序，但这不是答案。

我该怎么办？

代码：

Imports System.Data
Imports System.Data.OleDb

Public Class TestMe2

  Private lblSelector As New Label
  Private cbSelector As New ComboBox
  Private bsSelector As New BindingSource
  Private daMaster As New OleDbDataAdapter
  Private dgMaster As New DataGrid
  Private bsMaster As New BindingSource
  Private dgLookup As New DataGrid
  Private bsLookups As New BindingSource
  Private dsGFF As New DataSet
  Private cnn As New OleDbConnection

  Public Sub New()

    ' This call is required by the designer.
    InitializeComponent()

    ' Add any initialization after the InitializeComponent() call.
    Me.Controls.Add(lblSelector)
    lblSelector.Location = New System.Drawing.Point(0, 0)
    lblSelector.Text = "FileType"
    Me.Controls.Add(cbSelector)
    cbSelector.Location = New System.Drawing.Point(Me.lblSelector.Width, 0)
    Me.Controls.Add(dgMaster)
    dgMaster.Location = New System.Drawing.Point(0, cbSelector.Height)
    dgMaster.Height = 300
    dgMaster.Width = 2000
    Me.Controls.Add(dgLookup)
    dgLookup.Location = New System.Drawing.Point(0, cbSelector.Height + dgMaster.Height)
    dgLookup.Height = 100
    dgLookup.Width = 1000

  End Sub

  Private Sub TestMe2_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

    bsSelector.DataSource = dsGFF
    cbSelector.DataSource = bsSelector
    bsMaster.DataSource = dsGFF
    dgMaster.DataSource = bsMaster
    bsLookups.DataSource = dsGFF
    dgLookup.DataSource = bsLookups
    GetData()
    bsMaster.DataSource = bsSelector
    bsMaster.DataMember = "FileTypesToGFFTranslator"
    bsLookups.DataSource = bsMaster
    bsLookups.DataMember = "GFFTranslatorToTranslations"
    'dgMaster.autoresizecolumns()

  End Sub

  Private Sub GetData()

    Dim command As New OleDbCommand
    Dim parameter As New OleDbParameter

    ' where's the data?
    Dim cnnString As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|\GFFTranslator.accdb"
    cnn = New OleDb.OleDbConnection(cnnString)

    ' set up up the selector
    Dim daSelector As New OleDbDataAdapter("SELECT FileType FROM vwFileTypeSelection", cnn)
    daSelector.Fill(dsGFF, "vwFileTypeSelection")
    bsSelector.DataSource = dsGFF
    bsSelector.DataMember = "vwFileTypeSelection"
    cbSelector.ValueMember = "FileType"
    cbSelector.DisplayMember = "FileType"
    daSelector.Fill(dsGFF)

    ' set up the master
    daMaster = New OleDbDataAdapter("SELECT * FROM GFFTranslator", cnn)
    daMaster.Fill(dsGFF, "GFFTranslator")
    daMaster.UpdateCommand = New OleDbCommand("UPDATE GFFTRanslator" & _
                                              "   SET FileType = ?" & _
                                              "     , FieldPosition = ?" & _
                                              "     , FieldType = ?" & _
                                              "     , StartRepeatingSection = ?" & _
                                              "     , FileTypeIdentifier = ?" & _
                                              "     , Flag = ?" & _
                                              "     , DataStart = ?" & _
                                              "     , DataLength = ?" & _
                                              "     , NextLine = ?" & _
                                              "     , Lookup = ?" & _
                                              "     , Title = ?" & _
                                              "     , ExtraInfo = ?" & _
                                              " WHERE FileType = ?" & _
                                              "   AND FieldPosition = ? ;")
    daMaster.UpdateCommand.Parameters.Add("@FileType", OleDbType.VarChar, 255, "FileType")
    daMaster.UpdateCommand.Parameters.Add("@FieldPosition", OleDbType.Integer, 4, "FieldPosition")
    daMaster.UpdateCommand.Parameters.Add("@FieldType", OleDbType.VarChar, 255, "FieldType")
    daMaster.UpdateCommand.Parameters.Add("@StartRepeatingSection", OleDbType.Boolean, 1, "StartRepeatingSection")
    daMaster.UpdateCommand.Parameters.Add("@FileTypeIdentifier", OleDbType.Boolean, 1, "FileTypeIdentifier")
    daMaster.UpdateCommand.Parameters.Add("@Flag", OleDbType.Boolean, 1, "Flag")
    daMaster.UpdateCommand.Parameters.Add("@DataStart", OleDbType.Integer, 5, "DataStart")
    daMaster.UpdateCommand.Parameters.Add("@DataLength", OleDbType.Integer, 5, "DataLength")
    daMaster.UpdateCommand.Parameters.Add("@NextLine", OleDbType.Boolean, 1, "NextLine")
    daMaster.UpdateCommand.Parameters.Add("@Lookup", OleDbType.Boolean, 1, "Lookup")
    daMaster.UpdateCommand.Parameters.Add("@Title", OleDbType.VarChar, 255, "Title")
    daMaster.UpdateCommand.Parameters.Add("@ExtraInfo", OleDbType.VarChar, 255, "ExtraInfo")

    ' set up the lookup
    Dim daLookup As New OleDbDataAdapter("SELECT * FROM Translations", cnn)
    daLookup.Fill(dsGFF, "Translations")

    ' link everything together
    Try
      Dim drMaster As New DataRelation("FileTypesToGFFTranslator" _
                                      , dsGFF.Tables("vwFileTypeSelection").Columns("FileType") _
                                      , dsGFF.Tables("GFFTranslator").Columns("FileType"))
      dsGFF.Relations.Add(drMaster)

      Dim dcMaster As DataColumn() = New DataColumn() {dsGFF.Tables("GFFTranslator").Columns("FileType"), dsGFF.Tables("GFFTranslator").Columns("FieldType")}
      Dim dcLookup As DataColumn() = New DataColumn() {dsGFF.Tables("Translations").Columns("FileType"), dsGFF.Tables("Translations").Columns("FieldType")}
      Dim drLookup As New DataRelation("GFFTranslatorToTranslations" _
                                      , dcMaster _
                                      , dcLookup)
      dsGFF.Relations.Add(drLookup)
    Catch ex As Exception
      MessageBox.Show("Error: " & ex.Message)
    End Try

  End Sub

  Protected Overrides Sub Finalize()
    Me.Validate()

    Me.daMaster.Update(dsGFF.Tables("GFFTranslator"))
    Me.dsGFF.AcceptChanges()

    MyBase.Finalize()
  End Sub

End Class

Answer 1

在下面的代码中，您将connection object传递给SELECT命令。

' set up the master
daMaster = New OleDbDataAdapter("SELECT * FROM GFFTranslator", cnn)

.Fill()方法完成后，您的connection object 已关闭。

daMaster.Fill(dsGFF, "GFFTranslator")

您现在正在尝试创建一个UPDATE命令，但是您没有传递一个连接对象供它使用。

daMaster.UpdateCommand = New OleDbCommand("UPDATE GFFTRanslator" & _
                                          "   SET FileType = ?" & _
                                          "     , FieldPosition = ?" & _
                                          "     , FieldType = ?" & _
                                          "     , StartRepeatingSection = ?" & _
                                          "     , FileTypeIdentifier = ?" & _
                                          "     , Flag = ?" & _
                                          "     , DataStart = ?" & _
                                          "     , DataLength = ?" & _
                                          "     , NextLine = ?" & _
                                          "     , Lookup = ?" & _
                                          "     , Title = ?" & _
                                          "     , ExtraInfo = ?" & _
                                          " WHERE FileType = ?" & _
                                          "   AND FieldPosition = ? ;")
daMaster.UpdateCommand.Parameters.Add("@FileType", OleDbType.VarChar, 255, "FileType")
daMaster.UpdateCommand.Parameters.Add("@FieldPosition", OleDbType.Integer, 4, "FieldPosition")
daMaster.UpdateCommand.Parameters.Add("@FieldType", OleDbType.VarChar, 255, "FieldType")
daMaster.UpdateCommand.Parameters.Add("@StartRepeatingSection", OleDbType.Boolean, 1, "StartRepeatingSection")
daMaster.UpdateCommand.Parameters.Add("@FileTypeIdentifier", OleDbType.Boolean, 1, "FileTypeIdentifier")
daMaster.UpdateCommand.Parameters.Add("@Flag", OleDbType.Boolean, 1, "Flag")
daMaster.UpdateCommand.Parameters.Add("@DataStart", OleDbType.Integer, 5, "DataStart")
daMaster.UpdateCommand.Parameters.Add("@DataLength", OleDbType.Integer, 5, "DataLength")
daMaster.UpdateCommand.Parameters.Add("@NextLine", OleDbType.Boolean, 1, "NextLine")
daMaster.UpdateCommand.Parameters.Add("@Lookup", OleDbType.Boolean, 1, "Lookup")
daMaster.UpdateCommand.Parameters.Add("@Title", OleDbType.VarChar, 255, "Title")
daMaster.UpdateCommand.Parameters.Add("@ExtraInfo", OleDbType.VarChar, 255, "ExtraInfo")

因此，要解决此问题，请执行以下操作：

"   AND FieldPosition = ? ;", cnn) // Pass your connection object here.

Datagridview INSERT / SELECT / DELETE失败

1 个答案: