试图了解各种表之间的数据库关系方法

Question

Need to know DB stucture accurate or not? Lets say there's customers / products / product_events

Where each customers can have multiple products, but a product can not have more than one customer, also each products can have multiple events

So here's what I have for example

customers           products                            product_events
-----------     ------------------------------      ------------------------
id | name           id | customer_id | name             id | product_id | event_title

as I guess this is one => many relationship

but here can be large number of products and some of them or lets say many of them (products) might not be assigned to customers (in other word not sold to customers)

So to keep list of products and customer's products' list seprate is that a good approach to have any intermediary table to define products' relationship to customer?

So how about this stucture

customers           products        customer_products                   
-----------     ---------------     ------------------------------      
id | name           id | name       id | customer_id | product_id   

product_events
---------------------
id | product_id | event_title

For most of usage of these structures would be fetch list of products events by particular customer

Answer 1

Having a customer_id column in the products table would mean that only one customer could have a particular product - eg, you and I could not both buy the same model laptop, which just doesn't sound right.

Having an intermediate customer_products table sounds like the right way to go.

Answer 2

By considering "Customer" and "PRODUCT" tables there are Many to Many relation ship between two table. therefore you need to create 3rd table to maintain relationship. that 3rd Table should include two Primary key of both relation tables and Other attributes that bone because of relationship. 3rd table primary key should be combination of both key from relation tables.