According to the Nmap web site, "Nmap offers no direct database output functionality". It did, however, recommend PBNJ to get your data to a database such as SQLite, MySQL, or Postgres. Looks promising---I'd give it a try.
Well right now I am using the nmap::parser library to parse my data and dump it into a database. I'm just curious because their doesn't seem be support for the "reason" and "reason_ttl" fields which my client wants to store....