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 graphically with an e-r diagram
a piano manufacturer wants to keep track of all the pianos it makes individually. each piano has an identifying serial number and a manufacturing completion date. each instrument represents exactly one piano model, all of which have an identification number and a name. in addition, the company wants to maintain information about the designer of the model. over time, the company often manufactures thousands of pianos of a certain model, and the model design is specified before any single piano exists. (20p)
a piano manufacturer (see (e) above) employs piano technicians who are responsible for inspecting the instruments before they are shipped to the customers. each piano is inspected by at least two technicians (identified by their employee number). for each separate inspection, the company needs to record its date and a quality evaluation grade. (14p)
the piano technicians (see (f) above) 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. (10p)
a vendor builds multiple types of tablet computers. each type has a type identification number and a name. the key specifications for each type include amount of storage space and display type. the company uses multiple processor types, exactly one of which is used for a specific tablet computer type; obviously, the same processor can be used in multiple types of tablets. each processor has a manufacturer and a manufacturer’s unique code that identifies it. (13p)
each individual tablet computer manufactured by the vendor (see h above) is identified by the type identification number and a serial number that is unique within the type identification. the vendor wants to maintain information about when each tablet is shipped to a customer. (17p)
each of the tablet computer types (see (h) above) has a specific operating system. each technician the company employs is certified to assemble a specific tablet type – operating system combination. the validity of a certification starts on the day the employee passes a certification examination for the combination, and the certification is valid for a specific period of time that varies depending on tablet type – operating system combination. (11p)
grading schema:
1)correct answer for degree in i) – 1p
2)correct answer for cardinalities in i) – 1p
3)entity with complete set of attributes including key attributes +4p
4)incomplete set of attributes – (minus)-1p
5)absence of key attributes if they defined – (minus)-1p
6)no or wrong attributes – (minus)-1p
7)relationship with attributes +4p
8)wrong left arrowhead – (minus)-1p
9)wrong right arrowhead – (minus)-1p
10)absence of relationship attributes – (minus)-1p
11)relationship without attributes +3p
12)wrong left arrowhead – (minus)-1p
13)wrong right arrowhead – (minus)-1p