Another simple approach might be (if you don't want to use BCS), create Data Access Layer/Repository using Entity Framework or Enterprise Library, to read data from database as DTO objects. Then bind the DTO objects in dropdown. One simple code might be:
ProductRepository productRepository=new ProductRepository();
var products=productRepository.GetAllProducts();
ddlProducts.DataSource=products;
...
Thanks,
Sohel Rana
http://ranaictiu-technicalblog.blogspot.com