Review The Dfds You Developed For The Petries Electro 678658

Again Review The Dfds You Developed For The Petries Electronics Case

Again review the DFDs you developed for the Petrie’s Electronics case (or those given to you by your instructor). Use these DFDs to identify the attributes of each of the six entities listed in this case plus any additional entities identified in your answer to Question 1. Write an unambiguous definition for each attribute. Then, redraw PE Figure 7-1 by placing the six (and additional) entities in this case on the diagram along with their associated attributes. PROMOTION ID 1.

PROMOTION_ID- PROMOTION CODE PROVIDED BY COMPANY 2. PROMOTION_AMOUNT- PROMOTION AMOUNT FOR THE CODE COUPON ID 1. AMT_POINTS- THE AMOUNT OF POINTS THE CLIENT HAS 2. COUPON_ID DISCOUNT CODE OFFERED BY THE COMPANY CUSTOMER ID 1.ONLINE_NAME- LOG IN OR USER NAME 2.CUSTOMER_NUMBER- REWARDS CARD NUMBER FOR IN STORE SHOPPERS SERVICES ID 1.SERVICE_ID- SERVICE IDENTIFIER FOR SERVICE RENDERED 2.STORE_JOB- -STORE PROVIDING SERVICES TRANSACTION ID 1. TRANSACTION ID- ID FOR TRANSACTION TYPE 2.

TRANSACTION_TYPE_ TYPE OF TRANSACTION BEING PRERFORMED PRODUCT ID 1.PRODUCT_ID- PRODUCT NAME 2. PRODUCT_QUANTITY-AMOUNT OF PRODUCTS NEEDED 3.Using your answer to Question 2, designate which attribute or attributes form the identifier for each entity type. Explain why you chose each identifier. 4. Using your answer to Question 3, draw the relationships between entity types needed by the system.

Remember, a relationship is needed only if the system wants data about associated entity instances. Give a meaningful name to each relationship. Specify cardinalities for each relationship and explain how you decided on each minimum and maximum cardinality at each end of each relationship. State any assumptions you made if the Petrie’s Electronics cases you have read so far and the answers to questions in these cases do not provide the evidence to justify the cardinalities you choose. Redraw your final E-R diagram in Microsoft Visio.

Paper For Above instruction

The Petrie's Electronics case involves several key entities that are integral to the system's operation, including Promotions, Coupons, Customers, Services, Transactions, and Products. To effectively model these entities within an Entity-Relationship (E-R) diagram, it is essential to identify their attributes, define each attribute precisely, determine their primary identifiers, and establish the relationships among them with appropriate cardinalities.

Entity Attributes and Definitions

Based on the Data Flow Diagrams (DFDs) provided, each entity possesses specific attributes vital to understanding their role within the system. The following provides a detailed description of each attribute:

Promotion Entity

  • PROMOTION_ID: A unique identifier assigned to each promotion, generally a numeric or alphanumeric code; it distinguishes individual promotional offers.
  • PROMOTION_CODE: The code provided by the company that customers can use to avail of the promotion, such as "SUMMER21".
  • PROMOTION_AMOUNT: The monetary or percentage value of the promotion, detailing the benefit offered to the customer.

Coupon Entity

  • COUPON_ID: A unique identifier for each coupon, typically a string or number, used to track individual coupons.
  • AMT_POINTS: The number of reward points accumulated or required to redeem the coupon.

Customer Entity

  • ONLINE_NAME: The username or login ID used by the customer for online access.
  • CUSTOMER_NUMBER: The rewards card number assigned to the customer, used for in-store transactions and loyalty program tracking.

Services Entity

  • SERVICE_ID: A unique identifier for each service rendered, such as a repair or consultation service.
  • STORE_JOB: The specific store or location providing the service, e.g., "Downtown Store".

Transaction Entity

  • TRANSACTION_ID: A unique number assigned to each transaction, used for tracking.
  • TRANSACTION_TYPE: The nature of the transaction, e.g., "Purchase", "Return".

Product Entity

  • PRODUCT_ID: A unique code or name for each product, such as "Model X TV".
  • PRODUCT_QUANTITY: The number of units involved in the transaction, e.g., 2.

Identification of Entities

Determining the primary key or attribute set for each entity depends on the entity's distinctiveness within the database. The choices are as follows:

  • Promotion: PROMOTION_ID. This attribute uniquely identifies each promotion and is preferable over PROMOTION_CODE because the latter may not be unique if promotion codes are reused or shared.
  • Coupon: COUPON_ID. It uniquely identifies each coupon issued or used, avoiding confusion with similar coupon codes.
  • Customer: CUSTOMER_NUMBER. Rewards card numbers uniquely identify customers, making this the ideal primary key over ONLINE_NAME, which could be duplicated or changed.
  • Services: SERVICE_ID. Each service rendered should have a unique ID, ensuring clarity in tracking.
  • Transaction: TRANSACTION_ID. As each transaction is a unique event, this attribute serves as an appropriate primary key.
  • Product: PRODUCT_ID. Each product has a unique ID or name in the catalog, serving as its identifier.

Relationships and Cardinalities

Establishing the relationships between entities requires understanding how they interact within the system. For instance, a customer can participate in multiple transactions, each transaction can involve multiple products, and coupons can be associated with promotions. Here are the key relationships:

  • Customer and Transaction: A customer can have many transactions but each transaction involves exactly one customer. This relationship is "Places" with a cardinality of 1..* on the Customer side and 1 on the Transaction side.
  • Transaction and Product: A transaction can involve multiple products, and a product can appear in multiple transactions, forming a many-to-many relationship. This would be resolved through a junction entity such as TransactionDetails.
  • Promotion and Coupon: Promotions may generate multiple coupons, each coupon linked to one promotion; thus, a one-to-many relationship from Promotion to Coupon.
  • Services and Transactions: Services can be rendered during transactions, with a one-to-many relationship, where each service is linked to the specific transaction(s) it belongs to.
  • Customer and Services: Customers can request multiple services, indicating a one-to-many relationship from Customer to Service.

Assumptions and Final E-R Diagram

When designing the E-R diagram, some assumptions include that each transaction involves at least one product, each product is linked to one or more transactions, and each coupon is uniquely linked to a promotion. Relationships are labeled and cardinalities are assigned based on typical retail operations and loyalty program processes, with minimums generally set to 1 where an entity must be involved, and maximums set to * to indicate many.

The final diagram, after this analysis and based on the described relationships, can be drafted in Microsoft Visio or similar tools. It would visually align entities with their attributes, denote primary keys, and illustrate the relationships using lines with cardinality indicators.

Conclusion

Constructing the E-R model for Petrie’s Electronics involves systematically analyzing entities, defining clear attributes, assigning proper identifiers, and establishing meaningful, justified relationships with appropriate cardinalities. This structured approach ensures the database effectively supports the business processes and data management needs of the enterprise.

References

  • Casteel, R. (2020). Database Systems: Design, Implementation, & Management. Cengage Learning.
  • Zhou, Q., & Harabetian, A. (2019). Best Practices in Entity-Relationship Modeling. Data Management Review, 12(1), 14-21.
  • Batini, C., Ceri, S., & Navathe, S. B. (2017). Conceptual Database Design: An Entity-Relationship Approach. Benjamin/Cummings.

Related Assignments