> > There are always design trade-offs. Let's investigate this simple > >example a bit more so we can better understand the benefits and risks of > >using simple-minded vs. impractical modelling approaches. :-)
Whatever. If using a plain old relational database system, one can hold contact information in a table separate from the patient's name in fact, given that one human entitymay carry different names, sexes, dates of birth [1] from time to time, there is some merit in using one table to hold identity, the rest or majority of the fields being linked from other tables, whose key is the identity from the first one. This applies to addresses, telephone and other contact numbers and so on. I infer that the design of the central registry of the NHS is defficient in this respect either from deliberate choice or oversight, since the NHS number may not change and people whose expressed sex changes get a new NHS number and medical record. The fields I'd look for in contact details include a TypeOf field saying if it is a voice number, data, fax, etc, and a rather free form field giving instructions on what purposes it might be used for and when to choose it - for human interpretation, and commonly left unpopulated. [1] as some form of error, or of deliberate obfuscation, and yet one would wish to bring all the records together under some circumstances. -- Adrian Midgley (Linux desktop) GP, Exeter http://www.defoam.net/
