至少对我来说很好，很规范.

Looks good, well normalised, to me at least.

我注意到每种产品只能属于一个公司.如果那是您的预期，那还好，否则您可以让产品拥有自己的PID并具有product_company关系表，该表可以让多个公司销售特定产品.取决于谁管理我猜的产品.

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.

我确实注意到，用户表称为用户"(复数)，其他表则为单数(公司"，产品").不过那只是小事.

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.