Object-relationship modelling: Difference between revisions

Revision as of 13:00, 2 April 2004

Revision as of 20:54, 21 April 2004

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'''Object-Relationshiprelationship Modelling'''modelling (ORM)''' is a technique for designing or describing [[relational database]]s. The method was devised by Terry Halpin.

In '''ORM''' and related technologies each database table can be thought of as an object. It should be named singularly because a collection of rows of the database can be considered a collection. Consider this; each table will have one or more parent tables and likewise each table can have one or more child tables, that is to say the arrangement is very similar to a set of spokes protruding from the center. Each column in each parent table should be considered to be a property of the object table. This typically would be a read only property, but it is possible to have it also be read and write however the effects would cascade into any other table that was a child of the parent table, in other words, all sybling tables. Each child table can be considered a collection of one or more things.