How to make relationships like Library's Circulation Desk?

[hya]

Hello 

 

I have 2 tables that named Discs and Users. How to make relationship between the tables that One User receive One Disc, AND the same disc not available for all users (Only available for One User) -(e.g. Circulation Desk at Libraries)? 

[webko]

Actually, it's a many to one relationship, as I expect a User could borrow more than one Disc.

 

Relate on the primary ID in the User table to the foreign UserID in the Disc (child) table.

 

Use a portal to display the Discs that a User has. If there is a relationship from the Disc table to the User table, have a calculation that flags that the Disc is unavailable.

 

Something like Count(User::PrimaryID) will either be blank or have 1 from the Disc table. If it has a 1, it's not available.