private void comboBoxcategories_SelectionChangeCommitted(object sender, EventArgs e)
{
int selectedCategoryId = (int)comboBoxcategories.SelectedValue;
selectedCategory = CategoryBusiness.GetCategoriesById(selectedCategoryId);
textBoxcatname.Text = selectedCategory.Name;
buttoncatdelete.Enabled = true;
buttoncatupdate.Enabled = true;
}