Advice on choosing a primary key
You need 2 tables: one called say, Fileset and the other FilesetFile


Fileset contains information about the group: source, owner, who and when etc
FilesetFile contains a foreign key to Fileset.


Example:

Fileset

FilesetID, PK
FilesetOwner
FilesetAddedBy
...


FilesetFile

FilesetID, PK, FK
FileSuffix, PK
FileContent (BLOB column say)
...


You can then create a computed column "FileName" that concatenates FilesetID and FileSuffix to generate the pattern you need above

Trying this with one table will end in failure.