BEST PRACTICE 1 Entity Relationship Diagram Dan Yu School of Information Studies Syracuse University

IST659_Best Practice1_Dan Yu

Content Introduction .......................................... 3 Best Practice .......................................... 3 Assessment ............................................ 6 Conclusions and Recommendations ....... 8 REFERENCE ............................................... 8 Appendix: Glossary .............................. 10

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Introduction Entity Relationship Diagram, or ERD, is a view diagram to show how each data connected to others and what elements are related to the one object. It is used for a system to manage the electronic resources. It based on the diagram to clearly show the relationship between the components of system. These components consist the system, such as the client, server, and process of business and so no. Chen introduced ERD in early 1976, and Teorey, Yany and Fry had extended the ER model with the diagram for the relational database design in the following. The ERD models, a given problem in terms of its essential elements and the interactions between those elements in a problem domain. The ERD can serve as the basis for databases, which store data about the problem domain, and which use, manipulate, and constrain that data. Nowadays, ERD has been widely used in the database design and system analysis. It brings out the following main issues: • • • • • Identify the entities and their relationships. Distinct the ambiguities. Build many-­‐to-­‐many. Judge what data should be storage. The degree of the relationships.

Best Practice An ERD is a way to visualize a relational database: each entity represents a database table, and the relationship lines represent the keys in one table that point to specific records in related tables. The specific goal of ERDs is to build a blue print for database system. In another word, the best ERD show the macroscopic view of the system. How to realize a best ERD? It should abide by the principles. For an ERD, it has 4 components of Entity Relationship diagram. They are Entity, Relationships, Cardinality and Attribute.

IST659_Best Practice1_Dan Yu

The following diagram (Figure 1) has showed the most basic ERD.

Figure 1. A Simple ERD

After the introduction of the four elements of ERD, it also has the develop