Hi,

I am trying to develop an online application like ebay using rubyonrails.
now my problem is how to design my database to support all these different product types each having different attributes without actually creating a table for each product type. also bear in mind that a product type may have sub category and also the sub category might have another sub category and so on.
did ebay actually created a model and a table for each of the product type because that's not very efficient ?

can some one please help me ?

no idea what ebay does

this might help you -- Categories and Subcategories

Thanks , the posting answer my first problem of how to store my data as a tree , now how can i represent each leaf as a product with different attributes. for example one leaf might be a computer desktop with a desktop attributes and one might be shoe do i need a separate table for each of these products ?

Thanks

no, one table for the products

if a product can belong to more than one category or subcategory, then you would need a many-to-many relationship table as well

but if a product is found under only one (sub)category, no matter at what level of the category hierarchy, then all you need is a category foreign key in the product table