Relational data model
Modelling data in tables with rows, columns and explicitly described relationships.
What is a relational data model?
A relational data model describes data as tables with rows and named columns. Keys identify records and connect related tables. The applicable keys and rules are explicitly defined. The visible order of rows is not a reliable part of the model; a query must specify sorting for ordered output.
In a fictional example, customer C-21 appears in a customer table. Service request S-8 contains a required customer identifier referring to that customer. A suitable foreign key can prevent the request from referring to a nonexistent customer. It does not automatically check whether the person acting may see the request or whether its justification meets business needs. Such access and business rules need additional definition and enforcement.
Sources
Related terms
- DatabaseAn organised collection of data that software can access selectively and apply changes to.
- SQLA language for defining, querying and changing data.
- Foreign keyA foreign key protects a defined reference between records through matching key values.
- Unique keyA unique key constrains values or combinations so they cannot occur more than once within the defined data scope.
- Object-relational mappingConnecting program objects to data in a relational database.
- Database queryA database query requests data under defined conditions. Selection, result scope and ordering should fit the work being done.
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