relational algebra


relational algebra

(database, theory)A family of algebra with a well-foundedsemantics used for modelling the data stored in relational databases, and defining queries on it. The main operationsof the relational algebra are the set operations (such asunion, intersection, and cartesian product), selection(keeping only some lines of a table) and the projection(keeping only some columns).

The relational data model describes how the data isstructured.

Codd's reduction algorithm can convert from relational calculus to relational algebra.

relational algebra

(1) The branch of mathematics that deals with relations; for example, AND, OR, NOT, IS and CONTAINS.

(2) In a relational database, a collection of rules for dealing with tables; for example, JOIN, UNION and INTERSECT.