Path: dp-news.maxwell.syr.edu!spool.maxwell.syr.edu!drn.maxwell.syr.edu!news.maxwell.syr.edu!newsfeed.icl.net!proxad.net!213.200.89.82.MISMATCH!tiscali!newsfeed1.ip.tiscali.net!news.cid.net!fu-berlin.de!uni-berlin.de!not-for-mail From: "Alan" Newsgroups: comp.databases,comp.databases.object,comp.databases.theory Subject: Re: Demo: Modelling Cost of Travel Paths Between Towns Date: Mon, 15 Nov 2004 10:01:25 -0500 Lines: 29 Message-ID: <2vrum5F2p65r1U1@uni-berlin.de> References: <4b45d3ad.0411071807.4cbd51f0@posting.google.com> <4b5394b2.0411081132.41b7a32a@posting.google.com> <4b45d3ad.0411081928.6a6907a4@posting.google.com> <4b5394b2.0411101203.5d1ba318@posting.google.com> <4b45d3ad.0411112047.56e519d7@posting.google.com> <4b45d3ad.0411141723.6847ab83@posting.google.com> X-Trace: news.uni-berlin.de rnDjmjml4/KbDpQK+6+8LgxlPBS1WLeog6y86FqyX5JEJDnYbn X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2800.1437 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1441 Xref: dp-news.maxwell.syr.edu comp.databases:41854 comp.databases.object:12815 comp.databases.theory:28215 "Neo" wrote in message news:4b45d3ad.0411141723.6847ab83@posting.google.com... > > Sounds like your DB cannot do arithmetic like SQL: > > That is true, TM/XDb2 does not have much to do with operations (except > possibly intersecting things, which may the basis for all other > operations). Currently TM/XDb2 does not know integers, floats, or how > to add/subtract. These have to be provided by user's code just as that > for other classes such as person, car, color, etc. > > > update people set age=age+1 where name='john' ; Too bad. > > While TM/XDb2 does not have built-in operations such as the above, > user can easily create code that will update the age of any thing > whose name is john and has an age, including that of things whose > class is unknow at design-time (ie a person, dog, cat, pig, plane, etc > in the future). Try coding that in RM. > It doesn't get a whole lot easier: UPDATE your_table SET age = age + 1 WHERE name = 'john' AND age IS NOT NULL ;