Base and Derived Relations
In a relational database, all data are stored and accessed via relations. Relations that store data are called "base relations", and in implementations are called "tables". Other relations do not store data, but are computed by applying relational operations to other relations. These relations are sometimes called "derived relations". In implementations these are called "views" or "queries". Derived relations are convenient in that they act as a single relation, even though they may grab information from several relations. Also, derived relations can be used as an abstraction layer.
Read more about this topic: Database Constraints
Famous quotes containing the words base, derived and/or relations:
“Were I as base as is the lowly plain,
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Yet should the thoughts of me, your humble swain,
Ascend to heaven in honour of my love.”
—Joshua Sylvester (1561–1618)
“In the case of our main stock of well-worn predicates, I submit that the judgment of projectibility has derived from the habitual projection, rather than the habitual projection from the judgment of projectibility. The reason why only the right predicates happen so luckily to have become well entrenched is just that the well entrenched predicates have thereby become the right ones.”
—Nelson Goodman (b. 1906)
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—Wolfgang Amadeus Mozart (1756–1791)