ممكن شرح مبسط للكود..؟

السلام عليكم..

ممكن شرح مبسسسسسط للكود هذا..؟وخصوصا عند زر الاضافة ..احسه ملخبط...اذا في كود اسهل منه ياليت..

Imports System.Data.SqlClient

Public Class frm_add_product

    Private da As New SqlDataAdapter("SELECT * FROM Products", cn)
    Private ds As New DataSet
    Private ProductsBS As BindingSource = New BindingSource
    Dim SQLstr As String = "SELECT * FROM Products"
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        MsgBox(cn.State.ToString)
    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        cn.Open()
        Try
            da.Fill(ds, "Products")
            dg.DataSource = ds.Tables("Products")
        Catch ex As Exception

        End Try
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click

        da.InsertCommand = New SqlCommand("INSERT INTO Products VALUES (@Product_id,@Cust_id,@Product_name,@Fare_product,@Price,@Qty_produced,@qty_sold,@Qty_damaged,@Qty_Remainder)", cn)
        da.InsertCommand.Parameters.Add("@Product_id", SqlDbType.Int).Value = TextBox1.Text
        da.InsertCommand.Parameters.Add("@Cust_id", SqlDbType.Int).Value = TextBox2.Text
        da.InsertCommand.Parameters.Add("@Product_name", SqlDbType.NVarChar).Value = TextBox3.Text
        da.InsertCommand.Parameters.Add("@Fare_product", SqlDbType.Int).Value = TextBox4.Text
        da.InsertCommand.Parameters.Add("@Price", SqlDbType.Money).Value = TextBox5.Text
        da.InsertCommand.Parameters.Add("@Qty_produced", SqlDbType.Int).Value = TextBox9.Text
        da.InsertCommand.Parameters.Add("@qty_sold", SqlDbType.Int).Value = TextBox6.Text
        da.InsertCommand.Parameters.Add("@Qty_damaged", SqlDbType.Int).Value = TextBox7.Text
        da.InsertCommand.Parameters.Add("@Qty_Remainder", SqlDbType.Int).Value = TextBox8.Text
        da.InsertCommand.ExecuteNonQuery()



    End Sub

    Private Sub Label2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label2.Click

    End Sub

    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        da.DeleteCommand = New SqlCommand("DELETE FROM Products WHERE Product_id = '" & Trim(TextBox1.Text) & "'", cn)
        ' da.DeleteCommand.Parameters.Add("@Product_id", SqlDbType.Int).Value = ds.Tables(0).Rows(ProductsBS.Position)(0)

        da.DeleteCommand.ExecuteNonQuery()

        'ds.Clear()

        da.Fill(ds)
    End Sub

    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        da.SelectCommand = New SqlCommand("SELECT * FROM Products ", cn)
        ds.Clear()
        Try
            da.Fill(ds, "Products")
            dg.DataSource = ds.Tables("Products")
        Catch ex As Exception

        End Try
    End Sub

    Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click
        Dim SavInto As New SqlCommand
        Dim DataAdapter1 As New SqlDataAdapter(SQLstr, cn)
        SavInto.Connection = cn
        SavInto.CommandType = CommandType.Text
        SavInto.CommandText = "DELETE FROM Products WHERE Product_id ='" & Trim(TextBox1.Text) & "'"
        'cn.Open()
        SavInto.ExecuteNonQuery()
        ds.Clear()
        DataAdapter1.Fill(ds, "Products")
        'cn.Close()
        MsgBox("تمت عملية الحذف في قاعدة البيانات بنجاح")
        ' ChangePosition()
    End Sub
End Class

وكمان يطلع لي الرساله التاليه عند اضافة سجل جديد ...مالمشكلة ..؟ومالحل..؟

ياااليت يكون الرد سريع..

جزااااكم الله كل خير...