In the late 90s, I was DJing a few parties for friends. I had about 20 CDs I had made with all of the songs I used to play, rather than bringing crates of CDs. It made it much more convenient... one carry-case with a bunch of CDs rather than a hundred CDs. The problem was that it was hard to find the CD i wanted.
I typed all of the songs, artists, and track/cd numbers into a simple flat-file database, and it had a simple interface to search through it, log which songs were played, and so on. I ran it on a 486 Gateway Handbook subnotebook computer, which made it easy to bring to a gig.