ECON 1 Lecture Notes - Lecture 14: Unique Key, Database, Conceptual Schema
Document Summary
15 introduction to er modeling: database design. Information systems design: database, applications, user interfaces, other service programs, data plays a central role in an information system. Logical schema physical design physical schema: conceptual design, represents the informal requirements of an application in terms of a conceptual schema that refer to a conceptual data model. In a way that is easy to understand: using graphical formalisms. Diamond always contains a name related to link: an occurrence of a relationship is an n-tuple made up of occurrences of entities, one for each of the entities involved. In n:n relationship types, some attributes may be determined by a combination of participating entities: must be specified as relationship attributes, ex: grade for student and examination. Identifiers: describe the concepts of the schema that allow the unambiguous identification of the entity instances, attributes and/or entities, they are specified for each entity in a model.
