hi daniyalnawaz,

nice ERM. Maybe it s a good idea to state some rules about the cardinalities, for example:

A product can belong to more then as on product category
or (shall it be: a product can belong to one category only)

As for the product options:

Relationship between option_group and option is non identifying (dotted line) . If so, there is no need for an identifying relationship between product_option and option_group.

If an option belongs to different option_groups, then I would prefer identifying relationship between option_group and option (there, option would be weak entity). Further an identifying relationship between option and product_option. No relationship between option_group and product_option. (One should avoid loops in ERM because sometimes they cause trouble by duplicating foreign keys.)

btw, to be exact, in that ERM product_option is not an entity, it is a many-to-many relationship between option and product (well, I know, most graphical ERM design tools usually replace many-to-many relationships by a (joining) entity).

The solution would be slightly different if you use product category from your 2nd ERM to control the assignment of options to products.

krs,
tesu