Update stock barang dengan VB.Net

Bagi agan yang membutuhkan codingan untuk update stock barang dengan menggunakan VB.Net,ini codingannya :

Public Sub simpan2()
conn.Open()
Dim a As Integer
Try
For a = 0 To DataGridView1.Rows.Count - 1
Dim dab = New OleDbDataAdapter("INSERT INTO detailpenjualan (dnpenjualan,kode_barang,nama_barang,jumlah,harga_barang,total_harga) VALUES('" & DataGridView1.Rows(a).Cells(0).Value & "','" & DataGridView1.Rows(a).Cells(1).Value & "','" & DataGridView1.Rows(a).Cells(2).Value & "','" & DataGridView1.Rows(a).Cells(3).Value & "','" & DataGridView1.Rows(a).Cells(4).Value & "','" & DataGridView1.Rows(a).Cells(5).Value & "')", conn)
Dim dataset As New DataSet
dab.Fill(dataset, "detailpenjualan")
Dim dab2 = New OleDbDataAdapter("update databarang set stok_barang = stok_barang - '" & DataGridView1.Rows(a).Cells(3).Value & "' WHERE kode_barang = '" & DataGridView1.Rows(a).Cells(1).Value & "'", conn)
Dim data As New DataSet
dab2.Fill(data, "databarang")
Next
MsgBox("Datagrid berhasil disimpan")
Catch ex As Exception
MsgBox("Data Berhasil Diapprove")
End Try
conn.Close()
End Sub

Private Sub cmdsave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdsave.Click
simpan2()
Clear()
Clear2()
generate()
cmdadd.Enabled = False
cmdsave.Enabled = False
cmdedit.Enabled = False
cmddelete.Enabled = False
End Sub