Week 3 Project

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Database Design with ER Diagrams

Designing a database requires both a conceptual and a physical design. The conceptual or logical design models the database from a business perspective. The organization’s data model should re�ect its key business processes and the decision-making requirements. Database designers document the conceptual data model with an entity-relationship (ER) diagram.

The boxes represent entities and the diamonds represent relationships. The 1 or M on either side of the diamond can either represent a one-to-many, one-to-one, or many-to-many relationship between the corresponding entities. The ER diagram shows that a customer can have more than one order. An order can have more than one item and an item can have more than one scheduled delivery.

The process of creating small, stable, �exible, and adaptive data structures from complex groups of data when designing a relational database is called normalization.

The two major types of distributed databases are:

Replicated databases: Can operate in an unconnected fashion. The entire database is duplicated on batch basis when online.

Partitioned databases: Consist of parts that are physically stored and maintained in one location and other parts that are stored and maintained in other locations. This design enables each remote CPU to store the necessary data to serve the local area. Changes and transactions from local �les are synchronized with the central database on batch basis.

Let us now learn how to transmit this data to remote locations of organizations, where users can use the data to extract valuable information. The spread of telecommunications and wireless networks has enabled data transmission.