The Case For Question 1: The Red Star Case RSC Is Car Phone
The Case For Question 1the Red Star Case Rsc Is Car Phone Holder M
The Red Star Case (RSC) is a car phone holder manufacturing company operating three factories located in different cities. Each factory specializes in producing specific types of car phone holders, such as those designed for different vehicle models like the Toyota Corolla. The company’s organizational structure includes employees working exclusively within these factories, with each employee residing in the same city as their respective factory. Importantly, every factory is managed exclusively by a single employee who works within that factory; however, this employee does not necessarily hold the position of factory manager and cannot oversee more than one site. It is mandatory for each factory to have exactly one manager, but not all employees serve as managers.
Some employees are assigned to work on multiple projects simultaneously, such as developing various car phone holder models. Additionally, certain employees supervise other employees, establishing a supervisory hierarchy, where each supervised employee reports to exactly one supervisor. Not all employees are supervised, but those who are have a single supervisor. The organizational and manufacturing relationships involve various role assignments, project allocations, and supervisory structures, which need to be captured via an ER diagram.
Your task is to develop a presentation layer ER diagram, depicting the entity types and relationship types involved in the RSC case, using Chen's notation. This diagram should clearly illustrate entities such as Factory, Employee, Project, and their relationships, including supervisory and management links. Use a diagramming tool such as draw.io to create this ER diagram. Reasoning and clarity in representing the entities and relationships are essential to accurately model the business scenario.
Paper For Above instruction
The Red Star Case (RSC) presents a complex organizational and operational scenario involving manufacturing factories, employees, projects, and supervisory relationships, all intricately linked through various roles and responsibilities. To accurately model this scenario in an Entity-Relationship (ER) diagram utilizing Chen's notation, we must first identify the core entities, their primary keys, and the relationships among them.
Entities, Primary Keys, and Foreign Keys
The primary entities in this context include Factory, Employee, and Project. The Factory entity can be uniquely identified by a Factory_ID, ensuring each factory is distinguishable within the diagram. The Employee entity is identified by an Employee_ID that uniquely distinguishes each employee.
Each factory has a designated manager, who is also an employee. To model this, the Employee entity will include a foreign key Factory_ID referencing the Factory entity, establishing the association between an employee and their factory. For managerial assignments, an attribute such as Is_Manager or an explicit management relationship can be used to mark the managerial role.
The Project entity is identified by a Project_ID. Employees may be assigned to multiple projects, and each project may involve various employees—representing a many-to-many relationship that requires an associative entity or relationship set.
Relationships among Entities
- Manages: Between Employee and Factory, indicating that an employee manages a factory. This is a one-to-one relationship since each factory has exactly one manager, and each manager manages only one factory.
- Works_In: Between Employee and Factory, representing that employees work within a specific factory. This is a many-to-one relationship, as employees are assigned to one factory, but each factory can have multiple employees.
- Assigned_To: Between Employee and Project, to indicate employee participation in projects. This is a many-to-many relationship, given employees can participate in multiple projects, and each project has multiple employees involved.
- Supervises: An employee supervises many employees, with the supervised employees having exactly one supervisor. This is a one-to-many recursive relationship on the Employee entity.
Purpose of the RUNWAY_SURFACE Entity
In the second part of the scenario, a separate RUNWAY_SURFACE entity is introduced, distinct from the RUNWAY entity. The purpose of creating this separate entity is to model the specific attribute of a runway—its surface type—as a dedicated entity rather than embedding it directly into the RUNWAY entity itself.
This design allows for better normalization and management of surface types, which can be shared across multiple runways in different airports. For example, multiple runways at various airports may have a surface type such as asphalt, concrete, or grass. By separating surface details into the RUNWAY_SURFACE entity, the model avoids redundancy, facilitates data consistency, and enables efficient updates if surface types change or need to be standardized. This structure is particularly beneficial when surface information is complex, requiring additional attributes like surface condition, measurement parameters, or maintenance records, all of which could be included in the RUNWAY_SURFACE entity.
Summary
In summary, the ER diagram for the RSC case should feature core entities such as Factory, Employee, and Project, with relationships capturing management, work assignments, and supervision. The diagram must also explicitly depict employee supervision as a recursive relationship. For the airports database, segregating runway surface information into a dedicated entity enhances relational integrity and data manageability, assisting pilots and airport staff with accurate, comprehensive runway data essential for safe landings, especially in less common landing scenarios.