//ADD NEW PRODUCT
        private void btnAdd_Click(object sender, EventArgs e)
        {
            frmAddEditProduct addForm = new frmAddEditProduct();

            addForm.addProduct = true;

            DialogResult result = addForm.ShowDialog();

            if (result == DialogResult.OK)
            {
                product = addForm.product;
                this.FillComboBox();
                cboProductCodes.Text = product.ProductCode;
                this.ShowProduct();
            }
        }
        //EDIT CURRENT PRODUCT
        private void btnEdit_Click(object sender, EventArgs e)
        {
            frmAddEditProduct editForm = new frmAddEditProduct();

            editForm.addProduct = false;   //editing
            editForm.product    = product; //use current product to pass data to product in editing form
            DialogResult result = editForm.ShowDialog();

            if (result == DialogResult.OK)
            {
                product = editForm.product; //new current product equal to edits made in editForm
                this.FillComboBox();
                cboProductCodes.Text = product.ProductCode;
                this.ShowProduct();
            }
            else if (result == DialogResult.Retry) //retry due to concurrency error
            {
                this.ClearControls();
                this.GetProduct(product.ProductCode); //re-get product based on product code
            }
        }
        //ADD NEW PRODUCT
        private void btnAdd_Click(object sender, EventArgs e)
        {
            frmAddEditProduct addForm = new frmAddEditProduct(); 
            addForm.addProduct = true;

            DialogResult result = addForm.ShowDialog();
            if (result == DialogResult.OK)
            {
                product = addForm.product;
                this.FillComboBox();
                cboProductCodes.Text = product.ProductCode;
                this.ShowProduct();
            }
        }
 //EDIT CURRENT PRODUCT
 private void btnEdit_Click(object sender, EventArgs e)
 {
     frmAddEditProduct editForm = new frmAddEditProduct();
     editForm.addProduct = false; //editing
     editForm.product = product; //use current product to pass data to product in editing form
     DialogResult result = editForm.ShowDialog(); 
     if (result == DialogResult.OK)
     {
         product = editForm.product; //new current product equal to edits made in editForm
         this.FillComboBox();
         cboProductCodes.Text = product.ProductCode;
         this.ShowProduct(); 
     }
     else if (result == DialogResult.Retry) //retry due to concurrency error
     {
         this.ClearControls();
         this.GetProduct(product.ProductCode); //re-get product based on product code 
     }
 }