Petries Electronics Case Questions & Solutions Chapter 7

Petries Electronics Case Questions Solutions Chapter 7pointsattachm

Review the DFDs developed for the Petrie's Electronics case, particularly the three Level 1 diagrams in the Project Workbook - Week 3 folder, as well as the Diagramver2 diagram. Using these DFDs, identify the attributes of each of the six entities listed in the case, based on Figure PE Figure 7-1 on page 230, and as depicted in the Visio diagram in the Project Workbook - Week 4 folder.

Write unambiguous definitions for each attribute, and then redraw PE Figure 7-1 to show the six (and any additional) entities along with their associated attributes, similar to Figure 7-21 on page 223.

List at least two attributes for each entity and describe each in a short sentence or bullet point. Determine which attribute(s) serve as the identifier for each entity, justifying your choices as attributes that uniquely identify each entity instance, in accordance with page 199 definitions.

Using your identified primary keys, draw the relationships between entity types necessary for the system; include meaningful relationship names, specify the cardinalities, and justify the minimum and maximum cardinalities based on the case details and your assumptions. Redraw the final E-R diagram in Microsoft Visio, incorporating the relationships, attributes, and cardinalities, consistent with the DFD and figures in the textbook and the provided diagrams.

Paper For Above instruction

Understanding the data architecture of Petrie’s Electronics requires a systematic analysis of its entities, attributes, and relationships. This process involves examining existing Data Flow Diagrams (DFDs), defining attributes with precision, identifying primary keys, and establishing meaningful relationships with appropriate cardinalities.

Identifying Entities and Attributes

The six primary entities in the Petrie’s Electronics case include Customer, Order, Product, Employee, Supplier, and Shipment. Using the DFDs from the case, one can identify key attributes for each entity, ensuring that they comprehensively describe each entity and facilitate data management.

Customer: This entity represents individuals who purchase products. Attributes include:

• Customer_ID: A unique identifier assigned to each customer.
• Name: The customer’s full name.

Unambiguous definitions:

• Customer_ID: An alphanumeric code that uniquely distinguishes each customer within the database.
• Name: The complete name of the customer as recorded in official records.

Order: This entity captures purchase transactions. Attributes include:

• Order_ID: Unique number assigned to each order.
• Order_Date: The date the order was placed.

Definitions:

• Order_ID: A unique code used to identify each order record.
• Order_Date: The specific date when the order was initiated.

Product: Items available for sale. Attributes include:

• Product_ID: Unique product identifier.
• Description: Textual description of the product.

Definitions:

• Product_ID: Distinct alphanumeric code assigned to each product.
• Description: Brief details describing the product’s features and specifications.

Employee: Staff members managing transactions. Attributes include:

• Employee_ID: Unique identifier for each employee.
• Name: Employee’s full name.

Definitions:

• Employee_ID: An alphanumeric code that uniquely identifies an employee.
• Name: The full name of the employee.

Supplier: Entities providing products. Attributes include:

• Supplier_ID: Unique identifier for each supplier.
• Company_Name: Name of the supplying company.

Definitions:

• Supplier_ID: A unique code for each supplier.
• Shipment: The process of dispatching products. Attributes include:
• Shipment_ID: Unique shipment number.
• Shipment_Date: Date when the shipment was sent.
• Finally, after defining all attributes, these are visually incorporated into the PE Figure 7-1 diagram to better understand entity relationships and attributes.
• Choosing Primary Keys
• Primary identifiers are selected to ensure each entity instance can be uniquely distinguished. For example:
• Customer_ID for customers, because it uniquely identifies each customer regardless of name duplication.
• Order_ID for orders, as each purchase transaction should have a unique order number.
• Product_ID for products, because each product type has a unique code.
• Employee_ID for employees, to distinguish personnel records accurately.
• Supplier_ID for suppliers, to uniquely identify supplying entities.
• Shipment_ID for shipments, as each shipment record must be individually identifiable.
• Defining Relationships and Cardinalities
• The relationships are established based on the business rules: for example, a Customer can place many Orders; each Order is linked to one Customer (one-to-many). Similarly, an Order can include many Products, and each Product can appear in many Orders, suggesting a many-to-many relationship, which would be resolved with a junction table in implementation.
• Between entities:
• Customer and Order: "Places," with a one-to-many cardinality (one customer can place many orders).
• Order and Product: "Contains," with a many-to-many cardinality, managed via an associative entity.
• Product and Supplier: "Supplied by," with a many-to-one relationship, assuming one product has a single primary supplier.
• Order and Shipment: "Includes," with one-to-one or one-to-many depending on shipment process policy.
• These relationships are visually integrated into the final ER diagram in Visio, with clear relationship names and accurate cardinalities, justified through the case’s business rules and Workflow.
• Conclusion
• Elucidating the entities, their attributes, identifiers, and relationships enhances the data model of Petrie’s Electronics. Building such a detailed ER diagram supports robust database design, facilitating effective data storage, retrieval, and business process automation, crucial to the operational success of the enterprise.
• References
• Elmasri, R., & Navathe, S. B. (2016). Fundamentals of Database Systems (7th ed.). Pearson.