The purpose is to be able to look to see if I have at least one copy of a song. Like, if my dad wants me to do something with a song he likes, I can look to see if I have it in one or more of my books.
I did try to use a spreadsheet, but by the time the file got up to 6 MB, it was operating so slowly, it was frustrating and irritating. It has more than 3600 entries right now, and I've given up adding any more. But I have several songbooks left.
I suppose I could consider this an opportunity to practice patience. I'm not sure I'm ready to practice that much patience, but it is an option, as patience is not one of my solid virtues and I could use the practice. I don't really want to, though....