is my database overdesigned ?

Question

ok im new to database design, please give me advices about this.

1 http://stackoverflow.com/questions/1823685/database-when-should-i-use-a-composite-index

im not sure what does index does, but i do know we should put it when it will be heavly loaded like for WHERE verified = 1 and in search like company.name = something. am i right ?

2 http://stackoverflow.com/questions/1277865/mysql-indexes-how-many-are-enough/1277986#1277986

is it just enough ?

3 http://stackoverflow.com/questions/3282510/database-normalization

is it just right?

Thanks.

edit*

rules.

1. each users( company member or owners ) could be a member of a company
2. each company have some member of users.
3. there are company admins ( ceo, admins) and there are company members ( inserts the products )
4. each company can have products.

for the number 3 i will add a bit at users_company - 1 is for admin - 0 is for members

Answer 1

Looks good, well normalised, to me at least.

I notice that each product can only belong to one company. If that's what you intended that's fine, otherwise you could have product have its own PID and have a product_company relation table, which would let more than one company sell a particular product. Depends who administers the products I guess.

I did notice that the user table is called 'users' (plural) and the others are singular ('company', 'product'). That's only a minor thing though.

Answer 2

The only comment I have is that you may want to consider just adding a mapping_id column to your users_company table and making CID and UID foreign keys, and add a UNIQUE constraint.

This way you can have a distinct Primary Key for records in that table which isn't dependent on the structure of your other tables or any of your business logic.

Answer 3

No good.

Example: I want multiple pictures of my product. Please let me upload more than one picture of my product!