Tuesday, September 21, 1999

90-728 MIS Lecture Notes 1

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

HW#3 Grade Distribution

0

10

20

30

40

50

60

70

10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170

Tuesday, September 21, 1999

90-728 MIS Lecture Notes 2

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 3

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

– transaction-in-rows

– transaction-in-columns

Example:

INSPECTION

Cleanliness Safety StructuralSoundness

vs:

INSPECTIONINSPECTION_TYPEM1

INSPLINKM 1

What are the pros and cons of each approach?

Tuesday, September 21, 1999

90-728 MIS Lecture Notes 4

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

– attribute of ESTABLISHMENT

– separate entity

Example:

vs:

What are the pros and cons of each approach?

PERMIT STATUS ESTABLISHMENThas a

1 M

(1,1) (0,M)

Permit ID

ESTABLISHMENTPERMIT has aPERMIT STATUS has a1M

Permit ID

1 M

(1,1)(1,1) (0,M)(0,M)

Tuesday, September 21, 1999

90-728 MIS Lecture Notes 5

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 6

School Bus Garage E-R Diagram

GAS_FILL_UP

EMPLOYEE_CODE

EMPLOYEEGAS_TANK_LEVEL

OIL_CHECK BUS REASON_CODEREPAIR

INSPECTION

Undergoes

Has a

(1,M)

(1,1)

1

M

Has a Has a Has a

Has a

PART

UndergoesUndergoes

INSPECTION_CODE

Undergoes

(1,M)1

(1,1)M

M 1(1,M)(1,1)

RPLINK(1,M)(1,1)

1M

(1,1)(1,M)

1 M

(1,M)

(1,1)

1

M

(1,1)

(10,10)1

M

(0,M)

(1,1)

1

M

(1,M)(1,1)

1M(1,M)1

(1,1)M

INSPLINK1M

(1,M)(1,1)

Tuesday, September 21, 1999

90-728 MIS Lecture Notes 7

School Bus Garage Case Relational Database Schema

tblReasonCode (Reason)Scheduled MaintenanceBreakdownBus Driver RequestResult of Inspection

tblClassificationCode (Classification)MechanicHelperSupervisor

tblInspectionOutcomeCode (Outcome)OKAdjustedReplaced

tblInspectionType(Type)FLBrakesFRBrakesRLBrakesRRBrakesFLTireFRTireRLOTireRLITireRROTireRRITire

tblEmployee (EmployeeID, Classification@, LName, FName, …)

tblBus (BusID, Make, CurrentOdometerReading)

tblRepair (RepairID, RepairDate, BusID@, MechanicID@, HelperID@, SupervisorID@,Reason@, RepairOdometerReading, WorkDescription)

tblPart (PartID, PartDescription, UnitCost)

tblRepairPartLink (RepairID@, PartID@, Quantity)

tblGasTankLevel (ReadingID, ReadingDate, ReadingTime, ReadingValue)

tblGasFillUp (FillUpID, BusID@, FillUpDate, GasOdometerReading, GallonsPumped)

tblOilCheck (OilCheckID, BusID@, OilCheckDate, QuartsAdded)

tblInspection (InspectionID, BusID@, InspectionDate, InspectionOdometerReading)

tblInspectionTypeLink (InspectionID@, Type@, Outcome@, Comment)

Derived Attributes:[ExtendedCost] = Quantity*[UnitCost][TotalCost] = Sum of [ExtendedCost]