Question

I’m new to database design,
please give me advice about this.

1 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 MySQL indexes – how many are enough?

is it just enough ?

3 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.