php mysql-connect 2 tables

[PHP_CHILD]

i have 2 tables, items and users.

item has => item_id(unique_1), item_describe,item_cost,item_unit_price

user => user_name, psws, last_name

 

so whenever user logins inside and adds a item, i want to connect that adding of items with the user.

 

may b looks simple, but i want to do it without adding any extra field in tables.. is that possible.. Or else if i make item_id as primary, then how should i proceed?

 

 

And if item_id is not unique, if 2 users have same items addition with same id,cost_price, how could that be achieved?? thnks in advance...

[Barand]

CREATE TABLE useritem (
user_id INT,
item_id INT,
PRIMARY KEY(user_id, item_id)
)

 

if an item can be owned by one or more users and users can have one or more items then you use a link table to reconcile the many to many relationship