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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. Relational Database Development So Far. E-R diagrams - PowerPoint PPT Presentation
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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]