Multiple primary keys possible?

[Guest]

Hello,

We have a lot of projects which have documents/records labeled by certain codes and the only thing which differences records between projects is the project_id. At the same time duplicate record_labels
in one project should be avoided.

At the moment the user is forced to select project first and then
the rest of the projects are filtered out. But I canM-4t use record_label
as a primary_key, because all projects can and will have identical values.
Filtering obviously doesn't make record_labels unique.

I think two primary keys: project_id and record_label could solve this problemM-^Eare there any possibilities?


-Sven