in reply to
Formatting a DBI/MySQL query from HTML form via Perl
There is a bit on natural language parsing --> SQL in Object Oriented Perl. I know I've seen someone else's code that worked on the problem too but it was 5 years ago and I don't remember who/where. A casual couple of searches on the CPAN didn't turn up anything complete.
If I were starting on this from scratch I'd revisit Conway's stuff (it's been years since I read it but his clarity of thought in problem solving is invaluable even if you go a different way in the end) and join the idea with SQL::Abstract.
When you're done, write some tests and release it! It would great to have available. If I missed something on the CPAN that already touches this problem space, please someone mention it.