Homework 3 Results Total points 166 Overall grades

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Homework #3 Results • Total points 166 • Overall grades: – – Average 132.

Homework #3 Results • Total points 166 • Overall grades: – – Average 132. 8 or 80% Minimum 0 Maximum 163 Standard Deviation 51 • Excluding zeros: – – Average: 151. 7 or 94. 8% Minimum 120 Maximum 163 Standard Deviation 8. 65 Tuesday, September 21, 1999 90 -728 MIS Lecture Notes 1

Relational Database Development So Far • E-R diagrams – Entities: essential data elements –

Relational Database Development So Far • E-R diagrams – Entities: essential data elements – Attributes: data element descriptors – Entity linkage categories: relationships, connectivity, cardinality • Relational Database Models – – Tables: correspond to entities Fields: correspond to attributes Relationships: correspond to business rules, connectivity Basic queries • Relational Database Applications – Data management – Tables – Forms How do we bring it all together in a real-world setting? Tuesday, September 21, 1999 90 -728 MIS Lecture Notes 2

Health Inspection Problem Extensions - I • Inspection event may be represented two ways:

Health Inspection Problem Extensions - I • Inspection event may be represented two ways: – transaction-in-rows – transaction-in-columns Example: vs: INSPECTION_TYPE 1 M INSPLINK M 1 INSPECTION What are the pros and cons of each approach? Tuesday, September 21, 1999 90 -728 MIS Lecture Notes 3

Health Inspection Problem Extensions- II • Permit could be treated as: – attribute of

Health Inspection Problem Extensions- II • Permit could be treated as: – attribute of ESTABLISHMENT – separate entity Example: PERMIT STATUS 1 Permit ID M has a (1, 1) vs: (0, M) ESTABLISHMENT Permit ID PERMIT STATUS 1 M has a (1, 1) (0, M) PERMIT M (1, 1) has a 1 (0, M) ESTABLISHMENT What are the pros and cons of each approach? Tuesday, September 21, 1999 90 -728 MIS Lecture Notes 4

Health Inspection Problem Extensions- III • INSPECTION and PERMIT (if included as an entity)

Health Inspection Problem Extensions- III • INSPECTION and PERMIT (if included as an entity) could be treated as: – one-to-one related with ESTABLISHMENT (snapshot) – many-to-one related with ESTABLISHMENT (life cycle) What are the pros and cons of each approach? Tuesday, September 21, 1999 90 -728 MIS Lecture Notes 5

School Bus Garage E-R Diagram Tuesday, September 21, 1999 90 -728 MIS Lecture Notes

School Bus Garage E-R Diagram Tuesday, September 21, 1999 90 -728 MIS Lecture Notes 6

School Bus Garage Case Relational Database Schema Tuesday, September 21, 1999 90 -728 MIS

School Bus Garage Case Relational Database Schema Tuesday, September 21, 1999 90 -728 MIS Lecture Notes 7