Chapter 2 described E-R diagrams and showed you how to read them. Before moving on to developing E-R diagrams (in Appendix A), you should expand upon your knowledge of E-R diagrams to ensure a solid understanding of entities and attributes.This knowledge aids in the development of solid data models that lead to effective database structures. Although the diagrams can appear complex at first, they provide a very useful high-level tool for understanding the complicated relationships that exist among data in typical firms. E-R diagrams permit users and/or developers to communicate with a common understanding of how different types of data relate, including data about entities and business events. This understanding also permits a decision maker to interpret reports and analyses correctly based on extracts from a database.
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