Inv_File_Details shows all files inventoried on any computer ever. There is nothing in the table that I see that ties it to a computer in vComputer.
For example, this SQL query:
SELECT vi.Name,
ifd.*
FROM Inv_File_Details ifd
JOIN vItem vi ON ifd._ResourceGuid=vi.Guid
Will return the Name, id, ResourceGuid, File Size, and File Extension of all executable files (.exe, .dll, etc) inventoried on ALL computers in the environment.
I think you may want to look in a different table if your goal is to see whether the program is installed on a given computer. For example, consider this SQL report:
SELECT vc.Name, arp.DisplayName, arp.DisplayVersion, arp.InstallDate, arp.InstallFlag
FROM Inv_AddRemoveProgram arp
JOIN vComputer vc ON vc.Guid=arp._ResourceGuid
WHERE DisplayName LIKE '%Skype%'
This report will show the computer name of any computer with Skype installed. It pulls from Inv_AddRemoveProgram which is populated by a Software inventory, which itself looks at the registry.
If you run this report, do you see computers with Skype installed?
If you then remove Skype from one or two of those computers and re-run a Software inventory on those computers, and re-run the above report, do the computers disappear from your report?