relational algebra

database, theory A family of algebra with a well-founded

semantics used for modelling the data stored in relationaldatabases, and defining queries on it. The main operations

of the relational algebra are the set operations (such as

union, 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 is

structured.

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

(1997-02-17)