The following question is based upon a Car-Service relation which records the details of transactions occurring in an Automotive Mechanic and Repair business. You may assume the data are representative.
CustName CustDOB ServiceDATE CarRego CarMade CarModel Service FEE Staff NAME Staff speciality Lois Price 8/09/1998 19/5/2023 1y568 Toyota Camry 199 Ali Service tech Justin Thyme 10/10/2000 8/4/2022 1y576 Honda CRV 400 Chip Auto body Stan Dupp 10/10/2000 9/5/2023 1t567 Toyota Camry 199 Ali General Jack Pott 29/03/1981 2/10/2022 1t158 Ford Focus Fifty Holly Service tech Lois Price 8/09/1998 1/8/2022 1y458 Tesla Model X 199 Ali Auto body Ina Minat 03/01/1991 15/9/2022 1i132 Holden Astra 190 Chip Auto body Mike Rafone 30/01/2004 15/9/2022 1l884 BMW Z4 One twenty Ali 99999 Ina Minat 03/01/1991 10/8/2019 1i123 Black car Astra 269 Ali General
You have been asked to design a relational database for this system. You know that there are problems with the current design and that it will need to be modified in order to work effectively. You need to write a 1–2-page report that addresses the following:
The current design of the Car-Service relation presents several issues that can lead to data redundancy, inconsistency, and inefficiencies in data management. This report identifies the specific problems associated with the existing design and proposes a new relational database schema that addresses these issues effectively.
Data Redundancy: The current design contains repeated information across multiple records. For instance, the customer "Lois Price" appears multiple times with different service records. This redundancy can lead to increased storage requirements and complicates data management, as any update to customer information must be made in multiple places.
Inconsistent Data: The presence of multiple entries for the same customer or vehicle can lead to inconsistencies. For example, if Lois Price's contact information changes, it must be updated in every record where her name appears. If one record is missed, it can result in conflicting information.
Lack of Normalization: The current design does not adhere to the principles of database normalization, particularly the first three normal forms (1NF, 2NF, and 3NF). For instance, the table combines multiple entities (customers, vehicles, services, and staff) into a single relation, which violates the principle of separating distinct entities.
Difficulties in Querying: The current design makes it challenging to perform complex queries. For example, if a user wants to find all services performed by a specific staff member or all services for a particular car model, the existing structure may require extensive filtering and may not yield efficient results.
Limited Scalability: As the business grows, the current design may struggle to accommodate new data types or relationships. For instance, if new services or staff specializations are introduced, the existing structure may require significant modifications.
To address the identified problems, I propose a new relational database schema that separates the data into distinct tables, each representing a specific entity. The proposed schema includes the following tables:
Customers Table:
Vehicles Table:
Services Table:
Staff Table:
Elimination of Redundancy: By separating customers, vehicles, services, and staff into distinct tables, the new design eliminates redundancy. Each piece of information is stored only once, reducing storage requirements and simplifying updates.
Consistency of Data: With a normalized structure, updates to customer or vehicle information are made in a single location, ensuring consistency across the database. This minimizes the risk of conflicting data.
Adherence to Normalization Principles: The proposed design adheres to normalization principles, ensuring that each table represents a single entity and that relationships between entities are clearly defined through foreign keys. This enhances data integrity and reduces the likelihood of anomalies.
Improved Querying Capabilities: The new design allows for more efficient querying. Users can easily join tables to retrieve related information, such as all services performed on a specific vehicle or by a specific staff member, without extensive filtering.
Scalability: The modular nature of the proposed design allows for easy expansion. New services, staff members, or customer attributes can be added without significant restructuring of the database.
The current design of the Car-Service relation presents several challenges, including data redundancy, inconsistency, and difficulties in querying. By implementing a normalized relational database schema that separates distinct entities into individual tables, these issues can be effectively addressed. The proposed design not only enhances data integrity and consistency but also improves querying capabilities and scalability, making it a more robust solution for the Automotive Mechanic and Repair business.