使用ms access database通过visual basic 2012将数据插入数据库

Question

我正在使用MS Visual Basic 2012，我正在创建一个简单的编程，我面临的问题是“没有给出一个或多个必需参数的值”请帮帮我，看下面的代码

Public Class frmStudent
    Dim cnn As New OleDb.OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|\VBDatabase.accdb")

    Private Sub btnClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClose.Click
        Me.Close()
    End Sub

    Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClear.Click
        Me.txtstdID.Text = ""
        Me.txtStdName.Text = ""
        Me.txtFName.Text = ""
        Me.txtMName.Text = ""
        Me.txtAddress.Text = ""
        Me.txtstdID.Tag = ""
        'enable button edit
        Me.btnEdit.Enabled = True
        'set button add to add label
        Me.btnAdd.Text = "Add"
        '
        Me.txtstdID.Focus()
    End Sub

    Private Sub RefreshData()
        If Not cnn.State = ConnectionState.Open Then
            'open connection
            cnn.Open()
        End If

        Dim da As New OleDb.OleDbDataAdapter("SELECT StdID as [ID], " & _
                                             "StdName as [Name], Gender, ClassName, FName, MName, Address" & _
                                             " FROM tblStudent ORDER BY StdID", cnn)
        Dim dt As New DataTable
        'fill data to datatable
        da.Fill(dt)

        'offer data in data table into datagridview
        Me.dgvData.DataSource = dt

        'close connection
        cnn.Close()
    End Sub

    Private Sub btnAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAdd.Click
        Dim cmd As New OleDb.OleDbCommand
        If Not cnn.State = ConnectionState.Open Then
            'open connection if it is not yet open
            cnn.Open()
        End If

        cmd.Connection = cnn
        'check whether add new or update
        If Me.txtstdID.Tag & "" = "" Then
            'add new 
            'add data to table
            cmd.CommandText = "INSERT INTO tblstudent(StdID, StdName, Gender, ClassName, FName, MName, Address) " & _
                            " VALUES(" & Me.txtstdID.Text & ",'" & Me.txtStdName.Text & "','" & _
                            Me.cboGender.Text & "','" & Me.cboClassName.Text & "','" & Me.txtFName.Text & "','" & Me.txtMName.Text & "','" & _
                            Me.txtAddress.Text & "')"
            cmd.ExecuteNonQuery()
        Else
            'update data in table
            cmd.CommandText = "UPDATE tblStudent " & _
                        " SET StdID=" & Me.txtstdID.Text & _
                        ", StdName='" & Me.txtStdName.Text & "'" & _
                        ", Gender='" & Me.cboGender.Text & "'" & _
                        ", FName='" & Me.txtFName.Text & "'" & _
                        ", MName='" & Me.txtMName.Text & "'" & _
                        ", Address='" & Me.txtAddress.Text & "'" & _
                        " WHERE StdID=" & Me.txtstdID.Tag
            cmd.ExecuteNonQuery()
        End If
        'refresh data in list
        RefreshData()
        'clear form
        Me.btnClear.PerformClick()

        'close connection
        cnn.Close()
    End Sub

    Private Sub frmStudent_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        'TODO: This line of code loads data into the 'VBDatabaseDataSet1.tblStudent' table. You can move, or remove it, as needed.
        Me.TblStudentTableAdapter.Fill(Me.VBDatabaseDataSet1.tblStudent)
        cnn = New OleDb.OleDbConnection
        cnn.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|\VBDatabase.accdb"
        '
        'get data into list
        Me.RefreshData()
    End Sub

    Private Sub btnEdit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEdit.Click
        'check for the selected item in list
        If Me.dgvData.Rows.Count > 0 Then
            If Me.dgvData.SelectedRows.Count > 0 Then
                Dim intStdID As Integer = Me.dgvData.SelectedRows(0).Cells("ID").Value
                'get data from database followed by student id
                'open connection
                If Not cnn.State = ConnectionState.Open Then
                    cnn.Open()
                End If
                'get data into datatable
                Dim da As New OleDb.OleDbDataAdapter("SELECT * FROM tblStudent " & _
                                                     " WHERE StdID=" & intStdID, cnn)
                Dim dt As New DataTable
                da.Fill(dt)

                Me.txtstdID.Text = intStdID
                Me.txtStdName.Text = dt.Rows(0).Item("StdName")
                Me.cboGender.Text = dt.Rows(0).Item("Gender")
                Me.cboClassName.Text = dt.Rows(0).Item("ClassName")
                Me.txtFName.Text = dt.Rows(0).Item("FName")
                Me.txtMName.Text = dt.Rows(0).Item("MName")
                Me.txtAddress.Text = dt.Rows(0).Item("Address")
                '
                'hide the id to be edited in TAG of txtstdid in case id is changed
                Me.txtstdID.Tag = intStdID
                'change button add to update
                Me.btnAdd.Text = "Update"
                'disable button edit
                Me.btnEdit.Enabled = False
                'close connection
                cnn.Close()
            End If
        End If
    End Sub

    Private Sub btnDelete_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDelete.Click
        'check for the selected item in list
        If Me.dgvData.Rows.Count > 0 Then
            If Me.dgvData.SelectedRows.Count > 0 Then
                Dim intStdID As Integer = Me.dgvData.SelectedRows(0).Cells("ID").Value
                'open connection
                If Not cnn.State = ConnectionState.Open Then
                    cnn.Open()
                End If

                'delete data
                Dim cmd As New OleDb.OleDbCommand
                cmd.Connection = cnn
                cmd.CommandText = "DELETE FROM tblStudent WHERE StdID=" & intStdID
                cmd.ExecuteNonQuery()
                'refresh data
                Me.RefreshData()

                'close connection
                cnn.Close()
            End If
        End If
    End Sub

End Class