Adding sub-sets to primary key

[greeneyedjak]

I am trying to find a way to add sub-set identifiers to my primary key, i.e. "123" number field is an auto-entry serial primary key. I need to find a way to create 123-a, 123-b (which is a part of the same record, but has different info. Any suggestions.

[mr_vodka]

I wouldnt add a subset to a primary key. Instead I probably would go with a related table. If there is different info for a specific record, why wouldnt you make this related data?