I know every ecommerce database schema is difference. But is there a typical data model we can follow? I just do not want to reinvent the wheel and want to get a semi-standard data model to jump start my database design.

To be a little specific about my current challenge:

1. how to classify one product into multiple categories.
2. how to handle different set of product specifications, should I create a separate table for each type of products, such as tblElectronics, tblClothes, tblBooks, etc.

Any references are welcome. Thanks.