database compatibility

[ChadDavis]

Does anyone know of a resource ( on the web perhaps ) that discusses the
core differences between the different database's sql.  I'm trying to write
code that produces the correct sql for a variety of databases.  Such things
as Oracle's SEQUENCES versus mysql's AUTO_INCREMENT are of interest.  Maybe
I'm asking too much to find a summary of such differences.  But I'm only
interested in using mainstream sql functinality, nothing complicated.