On Sun, 13 Jul 2003, Vincent Hikida wrote: > Oops forgot to cc the list. > > > Unfortunately, intra-row functions using nulls return nulls. Inter-row > > functions "usually" ignore the nulls. I think there may be a few > exceptions. > > Though there is a relational theory which has is rigorously consistent, > > nulls are not part of the theory. Nulls are basically what > someone/somewhere > > thought of as a convenient tool (which it is) but has no theoretical > > underpinning and is dangerous. I use it because I feel that I have enough > > experience but perhaps I'll be stung one day. > > > > It has been discussed on the list before that in Oracle that in Oracle an > > empty string and null are the same. However Postgres treats an empty > string > > '' as an actual value and not as null. > > > > I just happened to notice another difference recently between Oracle and > > Postgresql for the clause > > > > WHERE 1 IN (1,2,NULL) > > > > In Oracle, this clause is false because 1 compared to a NULL is false.
If this is really true, then I believe Oracle does not implement this feature correctly. By my reading of SQL92, RVC IN IPV is equivalent to RVC =ANY IPV and in 8.7 GR2c, "If the implied <comparison predicate> is true for at least one row RT in T, then R <comp op> <some> T" is true which I believe holds for the case above. ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faqs/FAQ.html