Matakuliah
Tahun
Versi
: M0174/OBJECT ORIENTED DATABASE
: 2005
: 1/0
Pertemuan 2
Overview of data model
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Learning Outcomes
Pada akhir pertemuan ini, diharapkan mahasiswa
akan mampu :
• Mahasiswa dapat Menjelaskan konsep
tentang object data model (C2)
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Outline Materi
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Object Data models
A brief history of data models
First generation database technology
Second generation database technology
Third generation database technology
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Object Data models
• What is the object data models ?
• A data model has two important roles
– It is the basis for DBMSs
– It may be used to describe and analyse
database system
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A brief history of data models
• 1950s assembler language and machine
code
• 1960s COBOL and FORTRAN
• Database technology has continued to
evolve, in response to a need for more
sophisticated ways of managing,
administering, and using data
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A brief history of data models
• The first two generations of data models
were concerned mainly with representing
the meaning of data in terms of the
structure of the information represented.
• The third generation of data models, which
includes the object data model, in addition
represented the meaning of data in terms
of the behavior associated with the
information system.
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First generation database technology
– The first of database technology was based
upon network data model and the hierarchical
data model.
– In this model information is represented as
collections of interlinked record.
– The hierarchical model allows records to be
linked to form tree structure and the network
model allows records to be linked into network
structure
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First generation database technology
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First generation database technology
• The First Generation Data Model Limitation
– There is no clean separation between the logical
structure of the data and the way in which it is
physically implemented. Consequentially the interface
between programs and DBMS is complicated and a
knowledge of how the link record are implemented
often has to be written into the programs.
– The database languages manipulate only one record
at a time.
– There is no theoretical foundation for hierarchical and
network data model
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Second generation database technology
• The second generation of database
technology is based upon the relational
data model.
• The relational model represent all
information as table of data values.
• A table is used represent some type of real
world entity, or type of relationship entity,
and the row represent occurrences of the
entity or relationships
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Second generation database technology
• A strength of the relational model is that it has a
precise mathematical definition, and therefore
provide a theoretical model for database system.
• A table in a relational database is, in fact a
representation of a mathematical relation, and
operates which manipulate the tables are base
upon the corresponding mathematical operation
upon relation.
• In particular, the relation model includes an
algebra for manipulating the table, which provide
basis for new generation of database language
epitomized by SQL.
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Second generation database technology
• The Attractions of The Relational Models
– Mathematical Rigour
– Simplicity. All information is represented in the
relational model using one simple logical
structure, the table
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Second generation database technology
• Second Generation Data Model Limitation
– Tabular presentation is inappropriate for representing
the complex structure which exist in the real world.
– Behavioral limitation: Relational database language
express only a small subset of the ways in which data
can be manipulated. In order to define complex
computation upon data it is necessary to use other
programming language.
– Relational model supports only structural semantic,
not behavior semantics.
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Third generation database technology
• There are two dominant third generation data
models:
– Object Relational Data Model (ORDM)
– Object Oriented Data Model (OODM)
• ORDM are evolutionary approach, since the
adapt and enhance the relational model.
• Extensions to the relational model have been
defined to allow direct modeling of complex
structure, e.g, by allowing table to be nested and
by extensions to relational algebra to increase
its expressive power
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Third generation database technology
• Object Oriented Data Model are more
expressive than those of the previous
generations. They provide a richer
representation of the structure of the
information represented by the data than
is possible using first or second generation
models. Also they provide facilities for
representing within the database behavior
of the information represented by the data
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SUMMARY
• The Evolution of Data Models
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