tailieunhanh - PATTERNS OF DATA MODELING- P49

PATTERNS OF DATA MODELING- P49: Models provide the means for building quality software in a predictable manner. Models let developers think deeply about software and cope with large size and complexity. Developers can think abstractly before becoming enmeshed in the details of writing code. Although models are beneficial, they can be difficult to construct. That is where patterns come in. Patterns provide building blocks that help developers construct models faster and better. | 228 Appendix A Explanation of the UML Notation Figure UML generalization. References Blaha-2001 Michael Blaha. A Manager s Guide to Database Technology. Upper Saddle River New Jersey Prentice-Hall 2001. Blaha-2005 Michael Blaha and James Rumbaugh. Object-Oriented Modeling and Design with UML 2nd Edition. Upper Saddle River NJ Prentice Hall 2005. Chen-1976 PPS Chen. The entity-relationship model toward a unified view of data. ACM Transactions on Database Systems 1 1 March 1976 . Hoberman-2010 Steve Hoberman. Data Modeling Made Simple A Practical Guide for Business and IT Professionals 2nd Edition. Bradley Beach New Jersey Technics Publications 2010. Rumbaugh-2005 James Rumbaugh Ivar Jacobson and Grady Booch. The Unified Modeling Language Reference Manual Second Edition. Boston MA Addison-Wesley 2005. Appendix B Explanation of the IDEF1X Notation IDEF1X is the successor notation to IDEF Integrated Definition for Data Modeling . IDEF1X is a popular notation for modeling relational databases. The IDEF1X notation has been in use for two decades now and was effectively standardized through early adoption by the . Air Force. The major concepts in IDEF1X are entity types relationships and generalizations. Entity Type An entity is a concept abstraction or thing that can be individually identified and has meaning for an application. An entity type describes a group of entities with the same attributes kinds of relationships and intent. An entity type corresponds to a relational database table and an entity corresponds to a row in a table. The IDEF1X notation for an entity type is a box. IDEF1X differentiates between independent and dependent entity types. Figure shows three independent entity types. An independent entity type is an entity type that can exist on its own. Some authors call this a strong entity type. The IDEF1X symbol for an independent entity type is a square-corner box with the name of the entity type listed above the box. The top portion of the