Transcript Matakuliah : <<M0094>>/<<Pengantar Sistem Basis Data>> Tahun : <<2005>>

Matakuliah
Tahun
Versi
: <<M0094>>/<<Pengantar Sistem Basis Data>>
: <<2005>>
: <<1/1>>
Pertemuan <<21>>
<< Entity Relationship Diagram >>
1
Learning Outcomes
Pada akhir pertemuan ini, diharapkan mahasiswa
akan mampu :
Problem pada E-R diagram :Fan
TrapChasm TrapKasus E-R diagram
sebuah organisasi
2
Outline Materi
•
•
•
•
Problem pada E-R diagram :
Fan Trap
Chasm Trap
Kasus E-R diagram sebuah organisasi
3
Chapter 11
(lanjutan pert 20)
Entity-Relationship Modeling
Transparencies
4
Problems with ER Models
 Problems
may arise when designing a
conceptual data model called connection traps.
 Often
due to a misinterpretation of the
meaning of certain relationships.
 Two
main types of connection traps are called
fan traps and chasm traps.
5
Problems with ER Models
 Fan
Trap
– Where a model represents a relationship
between entity types, but pathway between
certain entity occurrences is ambiguous.
 Chasm
Trap
– Where a model suggests the existence of a
relationship between entity types, but pathway
does not exist between certain entity
occurrences.
6
An Example of a Fan Trap
7
Semantic Net of ER Model with Fan Trap

At which branch office does staff number SG37
work?
8
Restructuring ER Model to Remove Fan Trap
9
Semantic Net of Restructured ER Model
with Fan Trap Removed

SG37 works at branch B003.
10
An Example of a Chasm Trap
11
Semantic Net of ER Model with Chasm Trap
 At
which branch office is property PA14
available?
12
ER Model Restructured to Remove Chasm Trap
13
Semantic Net of Restructured ER Model
with Chasm Trap Removed
14
<< PENUTUP>>
Selanjutnya pert 22
PERLUASAN E-R
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