Record can only be chosen once.? How to do it

[Gediminas_Jonau]

How to disable the selection entry twice in the table.
Let’s say I have a list of equipment. I want to assign it to the classrooms.
One cabinet can have a lot of equipment.
But unique equipment can only be chosen once.

Is it possible and how to do it? Thank YOU.

[Kamille_Parks]

If you have a an [Equipment] table and a [Classroom] table:

Create a view in [Equipment] with a filter that is {Classroom} <is blank>. Set the {Equipment} linked field in the [Classroom] table to only select from that view.