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Data Models
Logical models - structures used represent a particualar organisation - Relational Model, OO Model
Conceptual models - descibe data in a manner independent of structure - Entity-Relationship Model
A data model is a combination of constructs used to organise data.
It provides a structuring mechanism - to allow the definition of new data types.
Object Data Model
Developed to overcome some of the limitations of the relational model.
Extends OO paradigm to databases.
Relational Data Model
Relational constructor makes it possible to organise data in a collection of records with a fixed structure.
A relation is represented by means of a table.
Rows show specific records - tuples - contain related values.
Columns correspond to fields of the record - attributes.
The order of rows and columns is irrelevant.
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Page updated August 31, 2004
