2. Reinterpreted Relationship Types When to use a Reinterpreted Relationship Type? Simple Case: If a relationship type is not used for connections to other model elements, he stays uninterpreted. If a relationship type is used for further modelling, he will either be reinterpreted or will become a multiple relationship type (n>2).
3. Generalization/Specialization (N,P) Therearevariousformsofstudents. The relationship is non-disjunct (N) because a PhDstudent in thesubject informationsystemscan also be a bachelorstudent in philosophy. The relationship is partial (P) becausethereare also othertypesof Students such asmasterstudents, executivemasterstudents, etc.
4. Generalization/Specialization (N,T) An animalcanbe male orfemaleorboth (e.g. snail) (not disjunct (N)). Therearenootherformsofsexuality (T). Tosomeextend
5. Generalization/Specialization (D,P) A personcaneitherbe a man or a woman (D). Thereare also othertypesliketransexuals (P) whoareneitherwomannor man. Tosomeextend
7. Modelling Conventions (Summary) Key Attribute consistof Name oftheEntity Type „ID“ or „Nr“ andhavetobeunderlined Non-Key Attributes will not beunderlined Key Attributes will bemodelledtoEntityTypesexclusively. Howandwhatkeys a relationship type receivesis due toitscardinalities. They will notbemodelled. The same is valid forForeignKeys. Additional Non-Key Attributes of a Relationship Type will bemodelled. Itisonlypossiblewith(x,n)-(x,n) relations (x=0 v x=1).
