Question

Convert your Conceptual model (Phase I) to a Logical model that can be implemented in a relational DBMS like Oracle. During this process you replace M-N relationships and multivalued attributes with constructs that can be implemented in the relational DBMS. Draw EER for the logical model after your modifications. Feel free to change your conceptual model (first delivery) if needed.

Answer 1

Converting conceptual model to logical model is described below.

Explanation:

The main aim of this model is to establish the entities, their attributes, and their relationships. In this Data modeling level, there is hardly any detail available of the actual Database structure.

The 3 basic tenants of Data Model are

• Entity: A real-world thing
• Attribute: Characteristics or properties of an entity
• Relationship: Dependency or association between two entities

For example:

• Customer and Product are two entities. Customer number and name are attributes of the Customer entity
• Product name and price are attributes of product entity
• Sale is the relationship between the customer and product

Characteristics of a conceptual data model

• Offers Organisation-wide coverage of the business concepts.
• This type of Data Models are designed and developed for a business audience.
• The conceptual model is developed independently of hardware specifications like data storage capacity, location or software specifications like DBMS vendor and technology. The focus is to represent data as a user will see it in the "real world."
• Conceptual data models known as Domain models create a common vocabulary for all stakeholders by establishing basic concepts and scope.

Logical Data Model

Logical data models add further information to the conceptual model elements. It defines the structure of the data elements and set the relationships between them.

The advantage of the Logical data model is to provide a foundation to form the base for the Physical model. However, the modeling structure remains generic. At this Data Modeling level, no primary or secondary key is defined. At this Data modeling level, you need to verify and adjust the connector details that were set earlier for relationships.

Characteristics of a Logical data model

• Describes data needs for a single project but could integrate with other logical data models based on the scope of the project.
• Designed and developed independently from the DBMS.
• Data attributes will have datatypes with exact precisions and length.
• Normalization processes to the model is applied typically till 3NF.