Modeling dynamic relationship types for subsets of entity type instances and across entity types |
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| Affiliation: | 1. Infosys Limited, Manikonda Village, Gachibowli, Rangareddy District, Hyderabad 500032, Andhra Pradesh, India;2. Microsoft R & D, Hyderabad, India;3. International Institute of Information Technology, Hyderabad, India;1. Ecological Sciences and Engineering Program, Purdue University, 550 Stadium Mall Dr., West Lafayette, IN 47907, United States;2. NEXTRANS Center, Purdue University, United States;3. School of Civil Engineering, Purdue University, United States;1. Universitat Politècnica de Catalunya, BarcelonaTech, Jordi Girona 1-3, Barcelona, Spain;2. Instituto Tecnológico de Buenos Aires, 25 de Mayo 457, Buenos Aires, Argentina;3. Instituto de Computación, Facultad de Ingeniería UdelaR, Ave Julio Herrera y Reissig 565, Montevideo, Uruguay;4. Aalborg Universitet, Selma Lagerlöfs Vej 300, Aalborg, Denmark;1. Gevirtz Graduate School of Education, University of California, Santa Barbara, CA USA;2. School of Industrial Engineering, Università Cattaneo – LIUC, Castellanza, VA, Italy;3. Graduate School of Education, University of California, Berkeley, CA, USA;1. University of Maryland Emergency Medicine Network, Baltimore, Maryland;2. Department of Emergency Medicine, University of Maryland School of Medicine, Baltimore, Maryland;3. Department of Emergency Medicine, Upper Chesapeake Health Systems, Bel Air, Maryland |
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| Abstract: | In a traditional ER model, once we specify a subclass or superclass relationship, any changes to that relationship are treated as schema evolution. Further, ER models are rigid in the sense that once a relationship type is specified across a set of entity types, an instance of relationship type occur when one instance of all participating entity types are specified. Therefore, it is difficult to introduce in a simplified manner all relationship types across subsets of given set of entity types. In this paper, we provide mechanisms to model in our extended ER model: (i) specification of dynamic relationship types across subsets of instances of entity types, (ii) a simplified specification of relationships across subsets of given set of entity types, and (iii) mapping our extended ER model to relational database schema. We also show through an e-contract example the utility of our extended ER model. |
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| Keywords: | ER model Star constructs Relational model e-Contract meta-model |
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