Re: managing variant data

Guten Tag Herr Scott, Montag, 25. Juni 2001, 11:21:42, schrieben sie: JS> Hi again, another conundrum. JS> What is the best way to deal with the following situation? JS> You have a group of common properties including a property that indicates a JS> second group of common properties. For example, JS> suppose you have this table: JS> Officers JS> ------------ JS> Name JS> Rank JS> Age JS> Height JS> Weight JS> Species JS> The 'Species' property may have the following values: Vulcan, Human, JS> Klingon, or Android. JS> If (Species==Vulcan) then you want to store these additional properties: JS> MindmeldCount and YearsOnVulcan JS> If (Species==Klingon) then you want to store these additional properties: JS> NumberofConcealedWeapons and RidgesOnForehead JS> If (Species==Android) then you want to store these additional properties: JS> PositronicBrain and MemoryJigas JS> If (Species==Human) then you want to store these additional properties: JS> AttendedStarfleetAcademy and BloodType JS> The problems I want to avoid are: JS> 1) placing all the properties for all species in the Officers table (as JS> this would include unnecessary properties for each row) and JS> 2) storing the properties in the Officers in four seperate tables JS> (Klingons, Humans, Androids, and Vulcans) redundantly. depends on what kind of DB you would like to use... on normal SQL-DBs you have to use something like Bill describes, on PostgreSQL you can use some feature like childs... says you make a officers-table with common values and then you make childs like klingon-officers, which "extends" officers. This means, that you all officers are automaticly stored in officers and the extra attributes are stored in the child-table. A third way is to use LDAP, there you can make an objectclass "officer" and a objectclass "klingon-officer" with the special attributes. Mit freundlichen Grüssen Felix Meulenkamp --------------------------------------------------- KDT Klaus Daten- und Telekommunikationstechnik GmbH Ein Unternehmen der Ision Internet AG, Hamburg Robertstrasse 6 * D-42107 Wuppertal, Germany tel +49 202 495-362 mailto:meulenkamp@kdt.de fax +49 202 495-399 http://www.kdt.de