组合框中的数据可在datagridview上查看

Question

Dim cnn As New OleDb.OleDbConnection
Dim cmd As New OleDb.OleDbCommand

Private Sub loadData()
    If Not cnn.State = ConnectionState.Open Then
        cnn.ConnectionString = "Provider=Microsoft.ACE.Oledb.12.0; Data Source=" & Application.StartupPath & "\LibrarySystem.accdb"
        'open connection
        cnn.Open()
    End If

    Dim da As New OleDb.OleDbDataAdapter("SELECT StatusID, StatusDesc FROM BookStatus", cnn)
    Dim dt As New DataTable

    'fill data to datatable
    da.Fill(dt)
    'show data in data table into combobox
    Me.cmbBookStatus.DataSource = dt
    Me.cmbBookStatus.DisplayMember = "StatusDesc"
    Me.cmbBookStatus.ValueMember = "StatusID"

    'close connection
    cnn.Close()

End Sub

我想在datagridview上显示组合框中的数据。以上是我使用的代码。我在bookstatus的microsoft访问中创建了一个表。但数据仍然没有显示在组合框中。有人可以帮助我吗？

我将用于在datagridview上查看组合框数据的代码放在保存按钮下。

Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click
    Dim cnn As New OleDb.OleDbConnection

    If Not cnn.State = ConnectionState.Open Then
        cnn.ConnectionString = "Provider=Microsoft.ACE.Oledb.12.0; Data Source=" & Application.StartupPath & "\LibrarySystem.accdb"
        cnn.Open()
    End If

    If (txtBookID.Text = "" And txtBookTitle.Text = "" And txtPub.Text = "" And txtAuthor.Text = "" And cmbBookStatus.SelectedValue = "") Then
        MessageBox.Show("Please insert all field!", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
    Else
        Dim msgbox As DialogResult = MessageBox.Show("Are you sure to save this record?", "Warning", MessageBoxButtons.YesNo, MessageBoxIcon.Question)

        If msgbox = Windows.Forms.DialogResult.Yes Then
            'add new data
            Dim cmd As New OleDb.OleDbCommand
            cmd.Connection = cnn
            cmd.CommandText = "INSERT INTO Book(BookID, Title, Publisher, Author, StatusID) " & _
            " VALUES('" & txtBookID.Text & "','" & txtBookTitle.Text & "','" & txtPub.Text & "','" & txtAuthor.Text & "','" & cmbBookStatus.SelectedValue & "')"

            cmd.ExecuteNonQuery()

            MessageBox.Show("Data has been recorded", "Add New Record", MessageBoxButtons.OK, MessageBoxIcon.Information)
            txtBookID.Clear()
            txtBookTitle.Clear()
            txtPub.Clear()
            txtAuthor.Clear()

        End If

        'refresh data          
        'Me.loadData()

        Dim db As New OleDb.OleDbDataAdapter("SELECT * FROM Book", cnn)
        Dim dt As New DataTable

        'fill data to datatable
        db.Fill(dt)
        'show data in data table into datagridview
        Me.dgvAddBook.DataSource = dt

        Dim column As DataGridViewColumn = dgvAddBook.Columns(1)
        column.Width = 269
    End If

    'close connection
    cnn.Close()

End Sub