Transform the relational schema developed in Problem and Exercise 9 into an EER diagram. State any assumptions that you have made.
Reference Problem and Exercise 9
Table 4-5 shows a shipping manifest. Your assignment is as follows:
a. Draw a relational schema and diagram the functional dependencies in the relation.
b. In what normal form is this relation?
c. Decompose MANIFEST into a set of 3NF relations.
d. Draw a relational schema for your 3NF relations and show the referential integrity constraints.
e. Draw your answer to part d using Microsoft Visio (or any other tool specified by your instructor).
Transform relational schema to EER (Enhanced Entity-Relationship) diagram
Entity-relationship model:
• It is used to represent data’s logically in business areas or in a service organization.
• It is most commonly used model for the communication between the end users and designers and it is used in the analysis phase of the system development.
• EER diagram is the specialised format of ER diagram.
Assumptions to transform relational schema to EER:
• There are some variations in the transformation.
• The assumptions made in this case are:
o A ship is operated by a captain
o Every shipment has a unique ID.
o Every ship carries consignments with some quantity and some identification number with it.
• Using the above assumptions, an EER diagram is modeled and shown below:
Cardinality notations in the relationship:
• In the above ER diagram, the relationship between entities CAPTAIN and SHIPMENT,
o One-to-many relationship is denoted here.
o A captain can be zero or one, who can operate many shipments or zero shipments.
• The relationship between entities SHIPMENT and SHIPMENT LINE,
o One-to-many relationship is denoted here.
o A shipment can handle many quantities.
• The relationship between entities SHIPMENT LINE and ITEM,
o Many-to-one relationship is denoted here.
o Many quantities contain a single item number.