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

• 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

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

• Object-Relational database system

A relational database system with:

– user defined Abstract Data Types (ADT)

– type constructors

– object identity

– reference types

– object identity

– reference types

– object identity

– reference types

– inheritance

– object identity

– reference types

– inheritance

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

Combination of atomic data types and their associated methods

• Type constructor• Type constructor

• Type constructor

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

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

list-of( base type )

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

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

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

• Operations for constructed types• Operations for constructed types

• Operations for constructed types

Field extraction (dot operation)

Set and multiset operations

List operations

Index reference

List operations

Index reference

List operations

Index reference

List operations

Index reference

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

• Objects, object identifiers, reference types

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

Every tuple (row) can be given object identifier

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)

• Inheritance• Inheritance

• Inheritance

Inheritance allows to reuse and refine already defined types

• 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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