1 object-relational model object-oriented database system

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Object-Relational ModelObject-Relational Model

• Object-Oriented database system• Object-Oriented database system

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• Object-Oriented database system

A programming language with a type system that allows any data to be persistent and supports XIII Commandments

• Object-Oriented database system

A programming language with a type system that allows any data to be persistent and supports XIII Commandments

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• Object-Relational database system• Object-Relational database system

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• Object-Relational database system

A relational database system with:



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– user defined Abstract Data Types (ADT)




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– type constructors





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– object identity





– object identity

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– object identity

– reference types





– object identity

– reference types

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– object identity

– reference types

– inheritance





– object identity

– reference types

– inheritance

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• Abstract Data Type (ADT) (B. Liskov, S. Ziles, 1976)


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Combination of atomic data types and their associated methods


Combination of atomic data types and their associated methods

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• Type constructor• Type constructor

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• Type constructor

A mapping of atomic data types and user-defined abstract data types into complex abstract data types



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row( n1 : t1, n2 : t2, …, nk : tk ) where ni is a field name and ti is a type




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list-of( base type )




list-of( base type )

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list-of( base type ) array-of( base type )




list-of( base type ) array-of( base type )

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list-of( base type ) array-of( base type ) set-of( base type)




list-of( base type ) array-of( base type ) set-of( base type)

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list-of( base type ) array-of( base type ) set-of( base type) bag-of( base-type )




list-of( base type ) array-of( base type ) set-of( base type) bag-of( base-type )

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• Operations for constructed types• Operations for constructed types

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• Operations for constructed types

Field extraction (dot operation)



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Set and multiset operations




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List operations




List operations

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List operations

Index reference




List operations

Index reference

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List operations

Index reference

Other




List operations

Index reference

Other

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• Objects, object identifiers, reference types• Objects, object identifiers, reference types

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• Objects, object identifiers, reference types

In object-relational model every tuple (row) can be considered as object



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Every tuple (row) can be given object identifier




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Object identifier can be used to refer to it from elsewhere in data

ref(base type)




Object identifier can be used to refer to it from elsewhere in data

ref(base type)

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• Inheritance• Inheritance

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• Inheritance

Inheritance allows to reuse and refine already defined types

• Inheritance


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• Inheritance


Substitution principle:

Given a supertype A and a subtype B, it is always possible to substitute an object of type B into a legal expression written for objects of type B, without producing errors

• Inheritance


Substitution principle:

Given a supertype A and a subtype B, it is always possible to substitute an object of type B into a legal expression written for objects of type B, without producing errors

1 object-relational model object-oriented database system

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