I am building a databased which handles the verification and calibration of Tools.
Diagram Below: Each tool has multiple verifications and calibrations. A test may be performed on several different tools and are related to the Tools by a join table. Each verification can have multiple lines, which is related to the Test 2 via a join for a look up. Calibrations are preformed externally and will not have multiple calibration lines, just a container field to import the certificate and basic text fields (10 or so fields)
I need to create a table for Memos, but I am not sure how to related the memo table to a the other tables.
A memo may be in relation to a test, a tool, verification or calibration. A memo could technically be related to multiple tools, but this is quite rare and I am the only user who will work in this database so I could easily just create a second memo. This will be a small database with record numbers in each table between (50 to possibly 5000).
How would you relate the memo to the various tables? My thought is having a Memo PK that is always populated & a Calibration PK, Tools PK, and Verification PK field where only one is populated. However I am not sure if this is a good structure or if I am likely missing a much better option. For ease I would like all of the Memos to live in the same table (I think).