Question

For each of the descriptions below, perform the following tasks:

i) Identify the degree and cardinalities of the relationship.
ii) Express the entities and the relationships with attributes in each description
1. Ebony and Ivory, a piano manufacturer, wants to keep track of all the pianos it makes. Each piano has an identifying serial number and a manufacturing completion date. Each instrument represents exactly one piano model. Each piano model has an identification number and a name. Over time, the company often manufactures thousands of pianos of a certain model, and the model design is specified before any single piano exists.
2. Ebony and Ivory employs piano technicians who are responsible for inspecting the instruments before they are shipped to the customers. Each piano is inspected by at least one technician (identified by their employee number). Each technician has a set one or more specialties. Some technicians may not be responsible for inspection jobs. For each separate inspection, the company needs to record its date and a quality evaluation grade.
3. The piano technicians have a hierarchy of reporting relationships: some of them have supervisory responsibilities in addition to their inspection role and have multiple other technicians report to them. The supervisors themselves report to the chief technician of the company.

Answer 1

1)i. The relationship is a degree of 2 ( i.e Binary). The cardinality of the relationship is One-to-Many.

ii. The model is from piano description to piano manufacturer.

PIANO:

Model name

Model number

Serial number

Manufacturing completion date

MANUFACTURER:

Ebony and Ivory

2)i. The relationship is a degree of 2 ( i.e Binary). The cardinality of the relationship is Many-to-Many.

ii. The model is from piano description to Technician.

PIANO:

Model name

Model number

Serial number

Manufacturing completion date

TECHNICIAN

Employee number

Specialty

3)i. The relationship is a degree of 2 (i.e Binary). The cardinality of the relationship is Many-to-One.

ii. The model is from Technician to Technician

TECHNICIAN:

Lower rank

TECHNICIAN:

Higher rank