Mind that the functionality is database dependant, hence you won't get the same results changing the db engine. Moreover you get different "rounding" errors trying to subtract similar dates.
Recent web2py's DAL supports an "epoch()" method that returns "seconds passed since 1-1-1970". If you can live with that, it's more deterministic and safer and works in the same way in all engines (e.g., need to develop on sqlite and in production use postgresql) and its functionality is supported on practically every db. On Thursday, November 22, 2012 9:55:04 PM UTC+1, dederocks wrote: > > Hi, > > If you have two datetime fields dta and dtb, a db().select(dta-dtb) will > return zero using the sqlite db, but a correct value if you use postgresql > for example. > The trick to make it work is to replace dta by julianday(dta) in the > select, e.g. db().select(julianday(dta)-julianday(dtb)). > > I guess not that easy to fix, especially since this substitution would > have to operate only when a datetime delta is computed? > > Or is there a way to do it I havent't found? > > Andre > --
