frmtitles.vb

来自「Programming Web and Desktop Applications」· VB 代码 · 共 314 行 · 第 1/2 页

        Me.btnLoad.Text = "&Load"
        '
        'btnUpdate
        '
        Me.btnUpdate.Location = New System.Drawing.Point(315, 10)
        Me.btnUpdate.Name = "btnUpdate"
        Me.btnUpdate.TabIndex = 1
        Me.btnUpdate.Text = "&Update"
        '
        'btnCancelAll
        '
        Me.btnCancelAll.Location = New System.Drawing.Point(315, 43)
        Me.btnCancelAll.Name = "btnCancelAll"
        Me.btnCancelAll.TabIndex = 2
        Me.btnCancelAll.Text = "Ca&ncel All"
        '
        'grdTitles
        '
        Me.grdTitles.DataMember = "Titles"
        Me.grdTitles.DataSource = Me.objdsTitles
        Me.grdTitles.HeaderForeColor = System.Drawing.SystemColors.ControlText
        Me.grdTitles.Location = New System.Drawing.Point(10, 76)
        Me.grdTitles.Name = "grdTitles"
        Me.grdTitles.Size = New System.Drawing.Size(646, 316)
        Me.grdTitles.TabIndex = 3
        '
        'frmTitles
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
        Me.ClientSize = New System.Drawing.Size(672, 421)
        Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.btnLoad, Me.btnUpdate, Me.btnCancelAll, Me.grdTitles})
        Me.Name = "frmTitles"
        Me.Text = "frmTitles"
        CType(Me.objdsTitles, System.ComponentModel.ISupportInitialize).EndInit()
        CType(Me.grdTitles, System.ComponentModel.ISupportInitialize).EndInit()
        Me.ResumeLayout(False)

    End Sub

#End Region

    Private Sub btnUpdate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnUpdate.Click
        Try
            'Attempt to update the datasource.
            Me.UpdateDataSet()
        Catch eUpdate As System.Exception
            'Add your error handling code here.
            'Display error message, if any.
            System.Windows.Forms.MessageBox.Show(eUpdate.Message)
        End Try

    End Sub
    Private Sub btnLoad_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLoad.Click
        Try
            'Attempt to load the dataset.
            Me.LoadDataSet()
        Catch eLoad As System.Exception
            'Add your error handling code here.
            'Display error message, if any.
            System.Windows.Forms.MessageBox.Show(eLoad.Message)
        End Try

    End Sub
    Private Sub btnCancelAll_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCancelAll.Click
        Me.objdsTitles.RejectChanges()

    End Sub
    Public Sub UpdateDataSet()
        'Create a new dataset to hold the changes that have been made to the main dataset.
        Dim objDataSetChanges As prjDataWizard.dsTitles = New prjDataWizard.dsTitles()
        'Stop any current edits.
        Me.BindingContext(objdsTitles, "Titles").EndCurrentEdit()
        'Get the changes that have been made to the main dataset.
        objDataSetChanges = CType(objdsTitles.GetChanges, prjDataWizard.dsTitles)
        'Check to see if any changes have been made.
        If (Not (objDataSetChanges) Is Nothing) Then
            Try
                'There are changes that need to be made, so attempt to update the datasource by
                'calling the update method and passing the dataset and any parameters.
                Me.UpdateDataSource(objDataSetChanges)
                objdsTitles.Merge(objDataSetChanges)
                objdsTitles.AcceptChanges()
            Catch eUpdate As System.Exception
                'Add your error handling code here.
                Throw eUpdate
            End Try
            'Add your code to check the returned dataset for any errors that may have been
            'pushed into the row object's error.
        End If

    End Sub
    Public Sub LoadDataSet()
        'Create a new dataset to hold the records returned from the call to FillDataSet.
        'A temporary dataset is used because filling the existing dataset would
        'require the databindings to be rebound.
        Dim objDataSetTemp As prjDataWizard.dsTitles
        objDataSetTemp = New prjDataWizard.dsTitles()
        Try
            'Attempt to fill the temporary dataset.
            Me.FillDataSet(objDataSetTemp)
        Catch eFillDataSet As System.Exception
            'Add your error handling code here.
            Throw eFillDataSet
        End Try
        Try
            'Empty the old records from the dataset.
            objdsTitles.Clear()
            'Merge the records into the main dataset.
            objdsTitles.Merge(objDataSetTemp)
        Catch eLoadMerge As System.Exception
            'Add your error handling code here.
            Throw eLoadMerge
        End Try

    End Sub
    Public Sub UpdateDataSource(ByVal ChangedRows As prjDataWizard.dsTitles)
        Try
            'The data source only needs to be updated if there are changes pending.
            If (Not (ChangedRows) Is Nothing) Then
                'Open the connection.
                Me.OleDbConnection1.Open()
                'Attempt to update the data source.
                OleDbDataAdapter1.Update(ChangedRows)
            End If
        Catch updateException As System.Exception
            'Add your error handling code here.
            Throw updateException
        Finally
            'Close the connection whether or not the exception was thrown.
            Me.OleDbConnection1.Close()
        End Try

    End Sub
    Public Sub FillDataSet(ByVal dataSet As prjDataWizard.dsTitles)
        'Turn off constraint checking before the dataset is filled.
        'This allows the adapters to fill the dataset without concern
        'for dependencies between the tables.
        dataSet.EnforceConstraints = False
        Try
            'Open the connection.
            Me.OleDbConnection1.Open()
            'Attempt to fill the dataset through the OleDbDataAdapter1.
            Me.OleDbDataAdapter1.Fill(dataSet)
        Catch fillException As System.Exception
            'Add your error handling code here.
            Throw fillException
        Finally
            'Turn constraint checking back on.
            dataSet.EnforceConstraints = True
            'Close the connection whether or not the exception was thrown.
            Me.OleDbConnection1.Close()
        End Try

    End Sub

End Class