将数据添加到数据库

Question

当我尝试将此数据放入我的数据库时，我遇到了问题 我使用Vstudio 2013和MS Access作为我的数据库

我的问题是每次我点击添加以在我的数据库中添加数据时此错误总是弹出对象引用未设置为对象的实例。即使我声明了

这是我的添加按钮代码

Dim cn As OleDb.OleDbConnection  
Dim cmd As OleDb.OleDbCommand

Private Sub btnAdd_Click(sender As Object, e As EventArgs) Handles btnAdd.Click

        Try


        If cn.State = ConnectionState.Open Then
            cn.Close()
        End If
        cn.Open()
        cmd.Connection = cn
            cmd.CommandText = "INSERT INTO gradess ( StudentNo,StudentName,StudentSection,SubjectNo1,SubjectNo2,SubjectNo3,SubjectNo4,SubjectNo5,SubjectNo6,SubjectNo7,SubjectNo8,TotalAverage) " & "Values('" & txtStudentNo.Text & "','" & lblName.Text & "','" & lblSection.Text & "','" & txtSubject1.Text & "','" & txtSubject2.Text & "','" & txtSubject3.Text & "','" & txtSubject4.Text & "','" & txtSubject5.Text & "','" & txtSubject6.Text & "','" & txtSubject7.Text & "','" & txtSubject8.Text & "','" & lblTotalAverage.Text & "')"

        cmd.ExecuteNonQuery()

        refreshlist()
        disablebutton()

        MsgBox("Successfully Added!!", vbInformation, "Successful")

            clear()
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try

    End Sub

Answer 1

您的声明应该是：Dim cn As New OleDb.OleDbConnection Dim cmd As New OleDb.OleDbCommand - F0r3v3r-A-N00b 20分钟前