Data Modeling with the Entity-Relationship Model - Database Processing: Fundamentals, Design, and Implementation - page 228

● A person may be a faculty member and an alumnus.
● A person may be a mentor and an alumnus.
● A current student cannot be a mentor.
● Each mentor may be an alumnus, but mentors are not required to be alumni.
● Alumni cannot, of course, be required to become mentors.
C. Extend and modify the E-R data model you created in part B to allow more data to be
recorded in the MPIS system. Use the IE Crow's Foot E-R model for your E-R diagrams.
Justify the decisions you make regarding minimum and maximum cardinality. The
MPIS needs to record:
● The date a student enrolled at Highline University, the date the student graduated,
and the degree the student received.
● The date an adviser was assigned to a student and the date the assignment ended.
● The date an adviser was assigned to work with a mentor and the date the assign-
ment ended.
● The date a mentor was assigned to a student and the date the assignment ended.
D. Write a short discussion of the difference between the three data models you have
created. How does data model B differ from data model A, and how does data model
C differ from data model B? What additional features of the E-R data model were intro-
duced when you created data models B and C?
The Queen anne Curiosity Shop wants to expand its database applications beyond the
current recording of sales. The company still wants to maintain data on customers,
employees, vendors, sales, and items, but it wants to (a) modify the way it handles
inventory and (b) simplify the storage of customer and employee data.
Currently, each item is considered unique, which means the item must be sold as a
whole, and multiple units of the item in stock must be treated as separate items in the
ITEM table. The Queen anne Curiosity Shop management wants the database modified
to include an inventory system that will allow multiple units of an item to be stored under
one ItemID. The system should allow for a quantity on hand, a quantity on order, and an
order due date. If the identical item is stocked by multiple vendors, the item should be
orderable from any of these vendors. The SaLE_ITEM table should then include Quantity
and ExtendedPrice columns to allow for sales of multiple units of an item.
The Queen anne Curiosity Shop management has noticed that some of the fields
in CUSTOMER and EMPLOyEE store similar data. Under the current system, when
an employee buys something at the store, his or her data has to be reentered into the
CUSTOMER table. The managers would like to have the CUSTOMER and EMPLOyEE
tables redesigned using subtypes.
a. Draw an E-R data model for The Queen Anne Curiosity Shop database schema shown
in Chapter 3. Use the IE Crow's Foot E-R model for your E-R diagrams. Justify the deci-
sions you make regarding minimum and maximum cardinality.
B. Extend and modify the E-R data model by adding only The Queen Anne Curiosity
Shop's inventory system requirements. Use the IE Crow's Foot E-R model for your E-R
diagrams. Create appropriate identifiers and attributes for each entity. Justify the deci-
sions you make regarding minimum and maximum cardinality.
C. Extend and modify the E-R data model by adding only The Queen Anne Curiosity Shop's
need for more efficient storage of CUSTOMER and EMPLOYEE data. Use the IE Crow's
Foot E-R model for your E-R diagrams. Create appropriate identifiers and attributes for
each entity. Justify the decisions you make regarding minimum and maximum cardinality.
D. Combine the E-R data models from parts B and C to meet all of The Queen Anne
Curiosity Shop's new requirements, making additional modifications, as needed. Use
the IE Crow's Foot E-R model for your E-R diagrams.
E. Describe how you would go about validating your data model in part D.