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MIS 3053
Database Design & Applications
The University of Tulsa
Professor: Akhilesh Bajaj
InClass ER Examples
Review of Lecture 1
• Entities and entity sets
• Attributes (simple / composite, single valued / multivalued,
null valued, derived)
• Relationships and relationship sets
• Attributes of relationship sets
• Degree of relationship sets
• Cardinality of relationship sets
Goals Today
• Review concepts we did in the previous class
• Practice Some Examples
Draw an ER Diagram
Source: http://www.cis.temple.edu/~vasilis/Courses/CIS616/Examples/E-R-diagrampractice-question.pdf
Draw an ER Diagram
City Cameras is an independent retailer of cameras, video-cameras and accessories. The
owner fulfils the roles of shopkeeper and manager and he purchases a variety of
products from a number of different suppliers.
The owner can check on different suppliers wholesale and recommended retail prices
with reference to their price lists, as shown.
During a normal day several customers will enter the shop and a number of them will
buy one or more of the products on sale.
At some stage the owner may decide that one or more product lines need to be reordered, following a visual stock-take. He will then consult the latest suppliers price lists
to see who is offering the best deals on given product lines.
Following this, he will ring one or more of the suppliers to order some of their products.
At the same time he will also make a written record of the orders that have been placed
with each supplier on a separate sheet of paper. These records are then used to verify
incoming orders and invoicing details.
Source: http://www.getahead-direct.com/gw-er-diagram-tutorial.htm
Write an English Description
Source: http://www.docstoc.com/docs/4211810/E-R-Diagram-(ERD)-Examples
ER Model Example
University Schema:
Objects: Courses, Course sections, Professors, Students (graduate and undergraduate)
, Classrooms, buildings
Example course numbers: MIS3053, MIS4233, MIS3023.
Example course section identifiers: MIS3053Fall2008A, MIS4233Fall2008A
Example StudentID: 0918512
Example FacultyID: 0918452
Example BuildingID: HELM, OLIP
Example classroom ID: HELM316
Events: A student takes a course section and gets a grade, a professor teaches a
course section and gets a rating for that course section, a graduate student may TA a
Course section, and also get a rating for it.
Example grade: ‘A’
Example Professor rating: “Excellent’
Example GA rating: ‘Excellent’
Let us write an ER diagram for this description