I don't know if it is used in any database for anything; but it is certainly used in the real world. Search for Fibonacci and Flowers, Shells and Bees Ancestry on a search engine to get started. These all have features that follow the Fibonacci Sequence. It would be more acccurate to say that Finonacci discovered the sequence, rather than that he invented it. It has been used in the "real world" for millions of years".

John