VB.NET Connect Database กับ VB แบบง่ายๆ

Imports System.Data
Imports System.Data.SqlClient
Public Class Form3
    Dim Conn As New SqlConnection
    Private Sub Form3_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Form1.Hide()
        Form2.Close()
        Form4.Close()
        DataGridView1.Refresh()
        Me.ProductTableAdapter.Fill_product(Me.DataSet1.product)
        DataGridView1.AlternatingRowsDefaultCellStyle.BackColor = Color.Bisque
        DataGridView1.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.DisplayedCells
        'TODO: This line of code loads data into the 'DataSet1.product' table. You can move, or remove it, as needed.


    End Sub
    Private Sub DataGridView1_CellContentClick(sender As Object, e As DataGridViewCellEventArgs) Handles DataGridView1.CellContentClick
        If (DataGridView1.CurrentRow.Cells(0).Selected) Then
            Button3.Enabled = True
            Button4.Enabled = True
        End If
        'TextBox1.Text = DataGridView1.CurrentRow.Cells(1).Value.ToString()
    End Sub

    Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
        Form2.Show()
    End Sub

    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        Form4.Show()
    End Sub

    Private Sub Button4_Click(sender As Object, e As EventArgs) Handles Button4.Click
        If MsgBox("แน่ใจหรือไม่จะลบสินค้านี้ ?", MsgBoxStyle.Question + MsgBoxStyle.YesNo, "ยืนยันการออกจากโปรแกรม") = MsgBoxResult.Yes Then

            With Conn
                If .State = ConnectionState.Open Then .Close()

                .ConnectionString = "Data Source=Dung-PC\sqlexpress; " & _
                  "Integrated Security=True; Initial Catalog=test_db; " & _
                  "Persist Security Info=False"

                .Open()

                If .State = 1 Then MsgBox("OK")

            End With

            Dim cmd As New SqlCommand("DELETE from product where product_id=" & DataGridView1.CurrentRow.Cells(0).Value.ToString() & "", Conn)
            If cmd.ExecuteNonQuery() Then
                MsgBox("Delete Product Success")
                Form1.reloadForm3()
            End If

        End If
    End Sub
End Class

With Conn
                If .State = ConnectionState.Open Then .Close()

                .ConnectionString = "Data Source=name-server\sqlexpress; " & _
                  "Integrated Security=True; Initial Catalog=test_db; " & _
                  "Persist Security Info=False"

                .Open()

                If .State = 1 Then MsgBox("OK")

            End With

            Dim cmd As New SqlCommand("DELETE from product where product_id=" & DataGridView1.CurrentRow.Cells(0).Value.ToString() & "", Conn)
            If cmd.ExecuteNonQuery() Then
                MsgBox("Delete Product Success")
                Form1.reloadForm3()
            End If