I forgot my son's ID, flying from Philadelphia to Orlando. It was a real nightmare, because he is a special needs adult..... They explained that they DO have ways to find people, in their data bases. Credit histories, etc. But DS? He has nothing like that. They were SO SO nice to me, I took all the blame, and I knew I really screwed up. They finally said, do you even have a prescription bottle with his name on it? Nope. They had to appeal to the head of the airport, I swear. AND then DS got a full pat down. We were the last to board the plane, the very last. For the trip home, I had my family FEDEX his ID to the hotel.
But based on our experience, they can look in the databases. I also had a friend PACK her ID in a bag she checked by mistake. Same thing, they let her on after extra security measures.