[python] 三层架构实例

Public Class dal_DealStudentInfo
  Public Function AddRecord(ByVal RecInfo As Student) As Boolean
    '……
    '连接数据库
    '……
    '……
    Try
      'SQL语句向数据库中写入数据
      '……
      Return True
    Catch
      Return False
    Finally
      '关闭数据库
    End Try
  End Function
  Public Function IsExist() As Boolean
    '查询数据库，如果存在该卡，则返回True，不存在则返回false
    If  '存在
      Return True
    Else
      Return False
    End If
  End Function
End Class

Public Class bll_ControlStudent
  Public Function AddStudent(ByVal student As Student) As String

    Dim DealStudent As New dal_DealStudentInfo
    If Not (DealStudent.IsExist) Then
      If DealStudent.AddRecord(student) Then
        Return "注册成功"
      Else
        Return "注册失败"
      End If
    Else
      Return "该卡已经存在，请重新输入卡号"
    End If
  End Function
End Class

Public Class frmRegister
  Private Sub btnOK_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnOK.Click
    Dim strMsg As String
    Dim student As New Student(Trim(txtCardNo.Text), Trim(txtStuName.Text), Trim(txtStuNo.Text), Trim(txtDepartment.Text), Val(txtMoney.Text))
    Dim ControlStudent As New bll_ControlStudent
    strMsg = ControlStudent.AddStudent(student)
    MessageBox.Show(strMsg)
  End Sub
  Private Sub btnCancel_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnCancel.Click
    Me.Close()
  End Sub
End Class