1 Pertemuan 25 Object Relational Database Management System Matakuliah : M0174/OBJECT ORIENTED DATABASE Tahun : 2005 Versi : 1/0
Jan 03, 2016
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Pertemuan 25Object Relational Database Management
System
Matakuliah : M0174/OBJECT ORIENTED DATABASE
Tahun : 2005
Versi : 1/0
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Learning Outcomes
Pada akhir pertemuan ini, diharapkan mahasiswa
akan mampu :
• Mahasiswa dapat Menghasilkan rancangan database objek (C3)
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Outline Materi
• Limitations of the second generation databases
• The nested relational data model
• Object relational data models
• SQL3
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Limitations of the second generation databases
• The main strengths of the Relational Data model are :– Simplicity
• All information is visible as values in tables
– Rigour• The relational data model has been defined with
theoretical rigour and provides a mathematical basis for researching issue such as database design, database language, and query optimisations
– Practicality and generality
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Limitations of the second generation databases
• In summary, the rules are:– All information must be represented as values
in tables– Each data item must be accessible by the
combination of table name, key value, and column name
– The RDBMS must support null values for representing missing or inapplicable information a systematic way
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Limitations of the second generation databases
– The database description (the schema) must be represented at the logical level as values in tables
– At least one relational database language should be expressible as strings of characters and have a well defined syntaxs
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The nested relational data model
• Nested Relational Data Model represent a data model which developed to close over lacking of relational data model in order to defining entities which complex.
• The nested relational data model remove the constraint that tables are flat.
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The nested relational data model
• In the nested relational data model, the values stored in tables can also be tables.
• The nested relational data model can be viewed as a step towards an object relational data model.
• NRDM table can be used to represent hierarchically structured entities. (this was also possible using the first generation) But NRDM also provides the strength of theoretical basis with its algebra
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The nested relational data model
• Example
Employee Number
E1
E2
Projects
Project_ Number hours
P1
P4
P1
10
5
20
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Object relational data models
• There are two general approaches towards third generation database technologies with integrate object-oriented features:Object Database – this extend object modelObject Relational Database – this extend the
relational data model to include data modeling features typically associated with object oriented system.
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Object relational data models
• In late 1980s, object & object relational database were seen as rivals, rather than complementary technologies.
• The respective visions of what the third generation database technology should be like were published by groups of leading researchers as “manifesto” documents – “the object oriented database manifesto” & “the third generation database manifesto”.
• The third generation database manifesto sees them as a means of extending a core relational data model
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SQL3
• SQL3 specification extends SQL to provide object oriented features but remains upwardly compatible with previous SQL standards. This feature include:Abstract Data Type (ADT)Generalization & Specialization hierarchiesAssertions & Triggers
• SQL3 provides two way to model entities as row and as ADT
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SUMMARY
• Object relational database extend the relational data model to address its weaknesses.
• In particular, object relational database have been developed to represent entities with complex structures & behavior such as exist in many scientific application, multimedia & GIS
• The main strengths of the Relational Data model are :– Simplicity– Rigour– Practicality and generality