Misalnya kita ingin mengetahui berapa hari seh range tanggal yang dipilih dari 2 buah datetime picker.
Misalnya terdapat tanggal awal dan tanggal akhir. dan kita ingin tahu berapa hari dari tanggal yang dipilih tersebut, function ini umpamanya akan berguna dalam pembuatan aplikasi Cuti misalnya yang diharuskan mengetahui berapa hari cuti yang diambil dari 2 buat tanggal.
Oke langsung saja, source codenya seperti dibawah ini

   1: Function hitungHari(ByVal dtp1 As DateTimePicker, ByVal dtp2 As DateTimePicker) As Integer

   2:         Dim a, b, c As Integer

   3:         a = dtp1.Value.DayOfYear

   4:         b = dtp2.Value.DayOfYear

   5:         c = dtp2.Value.DayOfYear - dtp1.Value.DayOfYear

   6:         If a > b Then

   7:             MessageBox.Show("Tanggal kedua harus lebih besar dari tanggal pertama", "Peringatan", MessageBoxButtons.OK, MessageBoxIcon.Information)

   8:             Return 0

   9:         ElseIf c > 365 Then

  10:             MessageBox.Show("Tidak boleh lebih dari satu tahun", "Peringatan", MessageBoxButtons.OK, MessageBoxIcon.Information)

  11:             Return 0

  12:         Else

  13:             Return c

  14:         End If

  15: End Function

Cara penggunaannya adalah sebagai berikut :

   1: Dim a As Integer = hitungHari(DateTimePicker1, DateTimePicker2)

   2: MsgBox(a)

Sekian dan terimakasih, semoga membantu.

Maksudnya adalah membuat sebuah combobox yang muncul di DataGridView dan combobox tersebut mempunyai event ataupun hal yang dilakukan jika combobox tersebut di change value nya atau indexnya. 

Oke langsung saja, implementasinya langsung ke contoh project saja yah, sekarang siapkan database access 2003 new database dan kasih nama latihan.mdb. dan buat beberapa table dengan ketentuan seperti berikut :

Relasinya jangan lupa ditentukan yah.

Buat tampilan di VB.NET kira-kira seperti ini dengan nama form nya yaitu frm_Transaksi:

 

Dan setiap objek dikasih nama sesuai dengan fungsinya yah..

Setelah itu new item lagi dan buat class baru dengan nama Cls_Induk.vb

Coding ini di dalam class tersebut :

   1: Imports System.IO

   2: Public Class Cls_Induk

   3:     Private myConnString As String

   4:     Private conn As OleDbConnection

   5:     'constructor

   6:     Public Sub New()

   7:         MyBase.New()

   8:         setConnString()

   9:         conn = New OleDbConnection

  10:         conn.ConnectionString = myConnString

  11:     End Sub

  12:     Private Sub setConnString()

  13:         myConnString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & Application.StartupPath & "\latihan.mdb"

  14:     End Sub

  15:     'pembebasan memori

  16:     Private Sub dispose()

  17:         conn = Nothing

  18:         myConnString = Nothing

  19:         GC.SuppressFinalize(Me)

  20:     End Sub

  21:     'destructor

  22:     Protected Overrides Sub Finalize()

  23:         dispose()

  24:     End Sub

  25:     Public ReadOnly Property connString() As String

  26:         Get

  27:             Return myConnString

  28:         End Get

  29:     End Property

  30:     Public Function openDB() As Boolean

  31:         If conn.State = ConnectionState.Open Then

  32:             conn.Close()

  33:         End If

  34:         Try

  35:             conn.Open()

  36:             Return True

  37:         Catch ex As Exception

  38:             Return False

  39:         End Try

  40:     End Function

  41:     Public Sub closeDB()

  42:         If conn.State = ConnectionState.Open Then conn.Close()

  43:     End Sub

  44:     Protected Function getDataTable(ByVal strSQL As String) As DataTable

  45:         Dim myAdapter As OleDbDataAdapter

  46:         Dim myData As New DataTable

  47:         Dim myCommand As OleDbCommand

  48:         openDB()

  49:         myCommand = New OleDbCommand(strSQL, conn)

  50:         myAdapter = New OleDbDataAdapter(myCommand)

  51:         myAdapter.Fill(myData)

  52:         closeDB()

  53:         Return myData

  54:         'pembebasan memori

  55:         myAdapter = Nothing

  56:         myData = Nothing

  57:         myCommand = Nothing

  58:     End Function

  59:     Protected Function getDataSet(ByVal strSQL As String) As DataSet

  60:         Dim myAdapter As OleDbDataAdapter

  61:         Dim myDataSet As New DataSet

  62:         Dim myCommand As OleDbCommand

  63:         openDB()

  64:         myCommand = New OleDbCommand(strSQL, conn)

  65:         myAdapter = New OleDbDataAdapter(myCommand)

  66:         myAdapter.Fill(myDataSet)

  67:         closeDB()

  68:         Return myDataSet

  69:         'pembebasan memori

  70:         myAdapter = Nothing

  71:         myDataSet = Nothing

  72:         myCommand = Nothing

  73:     End Function

  74:     'untuk errors

  75:     Protected Function insert(ByVal strSQL As String) As Boolean

  76:         Return execute(strSQL, "Insert Data")

  77:     End Function

  78:     Protected Function delete(ByVal strSQL As String) As Boolean

  79:         Return execute(strSQL, "Delete Data")

  80:     End Function

  81:     Protected Function update(ByVal strSQL As String) As Boolean

  82:         Return execute(strSQL, "Update Data")

  83:     End Function

  84:     Protected Function search(ByVal strSQL As String) As Boolean

  85:         Dim dt As New DataTable

  86:         dt = getDataTable(strSQL)

  87:         If dt.Rows.Count > 0 Then

  88:             Return True

  89:         Else

  90:             Return False

  91:         End If

  92:     End Function

  93:     Private Function execute(ByVal strSQL As String, ByVal tipePerintah As String) As Boolean

  94:         Try

  95:             Dim myCommand As OleDbCommand

  96:             myCommand = New OleDbCommand(strSQL)

  97:             openDB()

  98:             myCommand.Connection = conn

  99:             myCommand.ExecuteNonQuery()

 100:             closeDB()

 101:             'pembebasan memori

 102:             myCommand = Nothing

 103:             Return True

 104:         Catch ex As Exception

 105:             MessageBox.Show(ex.Message, tipePerintah, MessageBoxButtons.OK)

 106:             Return False

 107:         End Try

 108:     End Function

 109: End Class

Setelah itu buat lagi new item dan tambahkan class baru dengan nama Cls_Transaksi dan coding ini di class tersebut :

   1: Public Class Cls_Transaksi

   2:     Inherits Cls_Induk

   3:     Private strInit As String

   4:     Private KdTransaksi As String

   5:     Private Tanggal As String

   6:     Private Pelanggan As String

   7:     Private KdPetugas As Short

   8:     Private KdProduct As Short

   9:     Private Banyaknya As Integer

  10:     Private SubTotal As Double

  11:     Private Total As Double

  12:     Public Property setStrInit() As String

  13:         Get

  14:             Return strInit

  15:         End Get

  16:         Set(ByVal value As String)

  17:             strInit = value

  18:         End Set

  19:     End Property

  20:     Public Property setKdTransaksi() As String

  21:         Get

  22:             Return KdTransaksi

  23:         End Get

  24:         Set(ByVal value As String)

  25:             KdTransaksi = value

  26:         End Set

  27:     End Property

  28:     Public Property setTanggal() As String

  29:         Get

  30:             Return Tanggal

  31:         End Get

  32:         Set(ByVal value As String)

  33:             Tanggal = value

  34:         End Set

  35:     End Property

  36:     Public Property setPelanggan() As String

  37:         Get

  38:             Return Pelanggan

  39:         End Get

  40:         Set(ByVal value As String)

  41:             Pelanggan = value

  42:         End Set

  43:     End Property

  44:     Public Property setKdPetugas() As Short

  45:         Get

  46:             Return KdPetugas

  47:         End Get

  48:         Set(ByVal value As Short)

  49:             KdPetugas = value

  50:         End Set

  51:     End Property

  52:     Public Property setKdProduct() As Short

  53:         Get

  54:             Return KdProduct

  55:         End Get

  56:         Set(ByVal value As Short)

  57:             KdProduct = value

  58:         End Set

  59:     End Property

  60:     Public Property setBanyaknya() As Integer

  61:         Get

  62:             Return Banyaknya

  63:         End Get

  64:         Set(ByVal value As Integer)

  65:             Banyaknya = value

  66:         End Set

  67:     End Property

  68:     Public Property setSubTotal() As Double

  69:         Get

  70:             Return SubTotal

  71:         End Get

  72:         Set(ByVal value As Double)

  73:             SubTotal = value

  74:         End Set

  75:     End Property

  76:     Public Property setTotal() As Double

  77:         Get

  78:             Return Total

  79:         End Get

  80:         Set(ByVal value As Double)

  81:             Total = value

  82:         End Set

  83:     End Property

  84:     Public Sub New()

  85:         MyBase.New()

  86:         strInit = "SELECT ht.kdTransaksi,ht.Tanggal,p.NmPelanggan,tk.NmToko,pr.NmProduk,pr.Harga,dt.Banyaknya,dt.SubTotal,pt.NmPetugas from tbl_HTransaksi ht,tbl_DTransaksi dt,tbl_Produk pr,tbl_Petugas pt,tbl_Toko tk,tbl_Pelanggan p where ht.KdPelanggan=p.KdPelanggan and dt.KdProduk=pr.KdProduk and ht.KdPetugas=pt.KdPetugas and ht.KdToko=tk.KdToko and ht.KdTransaksi = dt.KdTransaksi"

  87:     End Sub

  88:     Private Sub dispose()

  89:         strInit = Nothing

  90:         GC.SuppressFinalize(Me)

  91:     End Sub

  92:     Protected Overrides Sub Finalize()

  93:         MyBase.Finalize()

  94:         dispose()

  95:     End Sub

  96:     Public Function getAll() As DataTable

  97:         Dim strSQL As String = strInit

  98:         Return MyBase.getDataTable(strSQL)

  99:     End Function

 100:     Public Function getProduk() As DataTable

 101:         Dim strSQL As String

 102:         strSQL = "select NmProduk from tbl_Produk order by KdProduk"

 103:         Return MyBase.getDataTable(strSQL)

 104:     End Function

 105:     Public Function getHargaProduk(ByVal nama As String) As DataTable

 106:         Dim strSQL As String

 107:         strSQL = "select KdProduk,Harga from tbl_Produk where NmProduk='" & nama & "'"

 108:         Return MyBase.getDataTable(strSQL)

 109:     End Function

 110:     Public Function getPetugas() As DataTable

 111:         Dim strSQL As String

 112:         strSQL = "select NmPetugas from tbl_Petugas order by KdPetugas"

 113:         Return MyBase.getDataTable(strSQL)

 114:     End Function

 115:     Public Function getKode(ByVal kode As String, ByVal nama As String, ByVal parNm As String, ByVal tbl As String) As DataTable

 116:         Dim strSQL As String

 117:         strSQL = "select " & kode & " from " & tbl & " where " & nama & " like '" & parNm & "'"

 118:         Return MyBase.getDataTable(strSQL)

 119:     End Function

 120:     Public Function getNoRek() As DataTable

 121:         Dim strSQL As String

 122:         strSQL = "select count(*) from tbl_HTransaksi"

 123:         Return MyBase.getDataTable(strSQL)

 124:     End Function

 125:     Public Overloads Function insertHTransaksi(ByVal obj As Cls_Transaksi) As Boolean

 126:         Dim strSql As String

 127:         strSql = "insert into tbl_HTransaksi values('" & obj.setKdTransaksi _

 128:         & "','" & obj.setTanggal _

 129:         & "','" & obj.setPelanggan _

 130:         & "','" & obj.setKdPetugas _

 131:         & "','" & obj.Total _

 132:         & "')"

 133:         Return MyBase.insert(strSql)

 134:     End Function

 135:     Public Overloads Function insertDTransaksi(ByVal obj As Cls_Transaksi) As Boolean

 136:         Dim strSql As String

 137:         strSql = "insert into tbl_DTransaksi(KdTransaksi,KdProduk,Banyaknya,Subtotal) values('" & obj.setKdTransaksi _

 138:         & "','" & obj.setKdProduct _

 139:         & "','" & obj.setBanyaknya _

 140:         & "','" & obj.setSubTotal _

 141:         & "')"

 142:         Return MyBase.insert(strSql)

 143:     End Function

 144: End Class

Dan terakhir coding ini di dalam form frm_Transaksi

   1: Public Class frm_Transaksi

   2:     Dim listCol As New DataGridViewComboBoxColumn

   3:     Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

   4:         DataGridView1.Rows.Clear()

   5:         bersih()

   6:     End Sub

   7:     Sub bersih()

   8:         txtJumlah.Text = ""

   9:         txtBayar.Text = ""

  10:         txtKembali.Text = ""

  11:         lblTampil.Text = ""

  12:         txtTuan.Text = ""

  13:     End Sub

  14:     Sub Petugas()

  15:         Dim dt As New DataTable

  16:         dt = TR.getPetugas()

  17:         cmbPetugas.DataSource = dt

  18:         cmbPetugas.DisplayMember = "NmPetugas"

  19:     End Sub

  20:     Sub Norek()

  21:         Dim dt2 As New DataTable

  22:         dt2 = TR.getNoRek

  23:         txtNota.Text = "TRASK000" & dt2.Rows(0).Item(0) + 1

  24:     End Sub

  25:     Sub Produk()

  26:         'Produk

  27:         DataGridView1.Columns.Remove("NamaBarang")

  28:         Dim dt As New DataTable

  29:         dt = TR.getProduk

  30:         listCol.DisplayIndex = 1

  31:         listCol.HeaderText = "NAMA BARANG"

  32:         'Masukkan nama field pada table yang akan di buat listcolom

  33:         listCol.DataPropertyName = "NamaBarang"

  34:         'Mengisi list dari Nama Produk table

  35:         listCol.DataSource = dt

  36:         listCol.DisplayMember = "NmProduk"

  37:         listCol.ValueMember = "NmProduk"

  38:         'Tambahkan column

  39:         DataGridView1.Columns.Add(listCol)

  40:         listCol.Width = 283

  41:     End Sub

  42:     Private Sub frm_Transaksi_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

  43:         Petugas()

  44:         Norek()

  45:         Produk()

  46:         'Membuat Readolny

  47:         DataGridView1.Columns(2).ReadOnly = True

  48:         DataGridView1.Columns(1).ReadOnly = True

  49:     End Sub

  50:     Private Sub DataGridView1_EditingControlShowing(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewEditingControlShowingEventArgs) Handles DataGridView1.EditingControlShowing

  51:         Dim cb As ComboBox = TryCast(e.Control, ComboBox)

  52:         If cb IsNot Nothing Then

  53:             If DataGridView1.Item(0, DataGridView1.CurrentRow.Index).Value <> "" Then

  54:                 RemoveHandler cb.SelectedIndexChanged, AddressOf DataGridView1_SelectedIndexChanged

  55:                 AddHandler cb.SelectedIndexChanged, AddressOf DataGridView1_SelectedIndexChanged

  56:             Else

  57:                 MessageBox.Show("Isi Data Banyaknya Terlebih Dahulu")

  58:             End If

  59:           End If

  60:     End Sub

  61:     Private Sub DataGridView1_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs)

  62:         Try

  63:             'Ketikkan sintaks untuk menampilkan data yang di inginkan

  64:             Dim comboBox1 As ComboBox = CType(sender, ComboBox)

  65:             Dim dt As New DataTable

  66:             dt = TR.getHargaProduk(comboBox1.Text)

  67:             DataGridView1.Rows(DataGridView1.CurrentRow.Index).Cells(1).Value = dt.Rows(0).Item("Harga")

  68:             Hitung()

  69:             Total()

  70:             txtBayar.ReadOnly = False

  71:             btnSimpan.Enabled = True

  72:         Catch

  73:             MessageBox.Show("Pilih produknya yah...!! ", "Informasi", MessageBoxButtons.OK, MessageBoxIcon.Information)

  74:             Exit Try

  75:         End Try

  76:     End Sub

  77:     Sub Hitung()

  78:         DataGridView1.Item(2, DataGridView1.CurrentRow.Index).Value = Format(CInt(DataGridView1.Item(0, DataGridView1.CurrentRow.Index).Value) * CInt(DataGridView1.Item(1, DataGridView1.CurrentRow.Index).Value), "Currency")

  79:     End Sub

  80:     Sub Total()

  81:         Dim Total As Double = 0

  82:         For i As Integer = 0 To DataGridView1.Rows.Count - 2

  83:             Total = Total + CDbl(DataGridView1.Item(2, i).Value)

  84:         Next i

  85:         txtJumlah.Text = Total

  86:         lblTampil.Text = Total

  87:     End Sub

  88:     Dim TR As New Cls_Transaksi

  89:     Sub InsertSet()

  90:         'insert ke Header Transaksi

  91:         Dim dt, dt1, dt2, dt3 As New DataTable

  92:         'mencari kode masing-masing dari table master

  93:         dt1 = TR.getKode("KdPetugas", "NmPetugas", cmbPetugas.Text, "tbl_Petugas")

  94:         TR.setKdPetugas = CInt(dt1.Rows(0).Item("KdPetugas"))

  95:         TR.setPelanggan = txtTuan.Text

  96:         TR.setKdTransaksi = txtNota.Text

  97:         TR.setTanggal = DateTimePicker1.Text

  98:         TR.setTotal = txtJumlah.Text

  99:         TR.insertHTransaksi(TR)

 100:         'insert ke Detail Transaksi sesuai dengan data yang di inputkan ke DATAGRIDVIEW oleh user

 101:         For i As Integer = 0 To DataGridView1.Rows.Count - 2

 102:             dt3 = TR.getKode("KdProduk", "NmProduk", DataGridView1.Item(3, i).Value, "tbl_Produk")

 103:             TR.setKdProduct = CInt(dt3.Rows(0).Item("KdProduk"))

 104:             TR.setBanyaknya = CInt(DataGridView1.Item(0, i).Value)

 105:             TR.setSubTotal = CDbl(DataGridView1.Item(2, i).Value)

 106:             TR.insertDTransaksi(TR)

 107:         Next i

 108:     End Sub

 109:     Private Sub btnSimpan_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSimpan.Click

 110:         If txtTuan.Text = "" Then

 111:             MessageBox.Show("Tentukan atau isi terlebih dahulu nama pelanggan", "Informasi", MessageBoxButtons.OK, MessageBoxIcon.Information)

 112:         Else

 113:             If CDbl(txtBayar.Text) > CDbl(txtJumlah.Text) Then

 114:                 btnTRBaru.Enabled = True

 115:                 InsertSet()

 116:                 MessageBox.Show("Data Tersimpan", "Informasi", MessageBoxButtons.OK, MessageBoxIcon.Information)

 117:                 btnSimpan.Enabled = False

 118:             Else

 119:                 MessageBox.Show("Anda uangnya kurang", "Informasi", MessageBoxButtons.OK, MessageBoxIcon.Information)

 120:                 txtBayar.Text = ""

 121:                 txtBayar.Focus()

 122:             End If

 123:         End If

 124:     End Sub

 125:     Private Sub btnTRBaru_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnTRBaru.Click

 126:         DataGridView1.Rows.Clear()

 127:         bersih()

 128:         btnSimpan.Enabled = True

 129:         btnTRBaru.Enabled = False

 130:         Norek()

 131:     End Sub

 132:     Private Sub txtBayar_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txtBayar.KeyPress

 133:         If e.KeyChar = Chr(13) Then

 134:             txtKembali.Text = CDbl(txtBayar.Text) - CDbl(txtJumlah.Text)

 135:             lblTampil.Text = CDbl(txtBayar.Text) - CDbl(txtJumlah.Text)

 136:         End If

 137:     End Sub

 138:     Private Sub btnKeluar_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnKeluar.Click

 139:         If MessageBox.Show("Apakah anda yakin akan keluar dari program ini ..??", "Konfirmasi", MessageBoxButtons.YesNo, MessageBoxIcon.Question) = Windows.Forms.DialogResult.Yes Then

 140:             Me.Close()

 141:         End If

 142:     End Sub

 143: End Class

Untuk lebih jelasnya silahkan download programnya disini