Data model: Difference between revisions

Revision as of 16:02, 27 January 2003

Revision as of 16:07, 27 January 2003

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# ''Querying:'' provides a language in which the data can be queried.

An example is the [[relational model]] in which the structure of data is defined as subsets of

[[n-arymathematical relation]]s. It furthermore defines a set of specific constraints (candidate keys, foreign keys, functional dependencies, multi-valued dependencies, join dependencies) and a general language for specifying constraints ([[first-order logic]]), and for manipulations and querying the data the [[relational algebra]], [[tuple calculus]] and [[___domain calculus]] are introduced.

Other examples are the [[Entity-Relationship Model]] and [[ORM]] although these usually only describe a small subset of the aspects described above.