Implementasi Object Oriented Programming di VB.NET akan membuat kode program VB.NET anda lebih mudah dalam proses maintenance kode program. Pada tutorial kali ini, kiita akan membuat class Induk dari Data Access Object DAOMaster.vb yang akan digunakan pada sub class Data Access Object pada implementasi di table database anda.

Pada tutorial ini penulis menggunakan database SQL Server dengan API VB.NET class-class System.Data.SqlClient

1. Class Master Data Access Object :: DAOMaster.vb

   Imports System.Data.SqlClient
   Public Class DAOMaster
   
       Private dbkon As DBKoneksi
       'variable nama_table akan di set oleh sub class
       Protected nama_table As String
       Public Sub New()
           'inisialisasi koneksi database ..
           dbkon = New DBKoneksi()
   
       End Sub
   
       Public Function koneksi() As DBKoneksi
           Return dbkon
       End Function
   
       Public Sub fillGrid(ByRef dg As DataGridView, _
                           ByRef sql As String)
           Dim cmd As SqlCommand
           Dim da As SqlDataAdapter
           Dim ds As DataSet
           cmd = New SqlCommand(sql, koneksi().openKoneksi())
           da = New SqlDataAdapter(cmd)
           ds = New DataSet()
           da.Fill(ds, "tbl")
           dg.DataSource = ds.Tables("tbl")
       End Sub
   
       Public Sub exeSQL(ByRef sql As String)
   
           Dim cmd As SqlCommand
           cmd = New SqlCommand(sql, koneksi().openKoneksi())
           cmd.ExecuteNonQuery()
           koneksi().closeKoneksi()
   
       End Sub
   End Class
   

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2. Berikut ini sub class dari DAOMaster yang bertanggung jawab terhadap tabel pegawai pada database
   nama classnya DAOPegawai

   Imports System.Data.SqlClient
   Public Class DAOPegawai
       Inherits DAOMaster
   
       Private dbkon As DBKoneksi
       Public Sub New()
           MyBase.New()
           nama_table = "pegawai"
       End Sub
   
      Public Function create() As Pegawai
           Return New Pegawai()
       End Function
   
      Public Sub simpan(ByRef obj As Pegawai)
           Dim sql As String
           sql = "INSERT INTO pegawai (nama,telpon) " & _
                 " VALUES ('" & obj.nama & "'," & _
                 "'" & obj.telpon & "')"
           exeSQL(sql)
       End Sub
   
      Public Sub delete(ByRef obj As Pegawai)
           Dim sql As String
           sql = "DELETE FROM pegawai WHERE id=" & obj.id
           exeSQL(sql)
       End Sub
   
      Public Sub isiGrid(ByRef dg As DataGridView)
           Dim sql As String
           sql = "SELECT * FROM pegawai ORDER BY a.nama"
           fillGrid(dg, sql)
       End Sub
   
   End Class
   

3. Berikut contoh kode program pada form yang didalamnya terdapat komponen DataGridView

   Public Class FormPegawai
       Dim dao As DAOPegawai
       Private Sub FormPegawai_Load(ByVal sender As System.Object, _
                            ByVal e As System.EventArgs) Handles MyBase.Load
           dao = New DAOPegawai()
           dao.isiGrid(DataGridView1)
       End Sub
   
       Private Sub btnSimpan_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSimpan.Click
   
           dim obj as Pegawai
           obj = new Pegawai()
           'set id pegawai = 1 akan dihapus ... test saja
           obj.id=1
   
           dao.delete(obj)
   
        End sub
   End Class