Relational algebra
database, theory
A family of algebra with a well-founded semantics used for modelling the data stored in relational databases, 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 relational calculus to relational algebra.
(1997-02-17)
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noun 1. an electronic database comprising multiple files of related information, usually stored in tables of rows (records) and columns (fields), and allowing a link to be established between separate files that have a matching field, as a column of invoice numbers, so that the two files can be queried simultaneously by the user. relational […]
- Relational language
language Any kind of programming language that specifies output in terms of some property and some arguments. For example, if Tom has two brothers, Dick and Harry, a relational language will respond to the query “Who is Tom’s brother?” with either Dick or Harry. Notice that unlike functional languages, relational languages do not require a […]
- Relational model
relational data model
- Relations
noun 1. an existing connection; a significant association between or among things: the relation between cause and effect. 2. relations. the various connections between peoples, countries, etc.: foreign relations. the various connections in which persons are brought together: business and social relations. sexual intercourse. 3. the mode or kind of connection between one person and […]
- Relationship
[ri-ley-shuh n-ship] /rɪˈleɪ ʃənˌʃɪp/ noun 1. a connection, association, or involvement. 2. connection between persons by blood or marriage. 3. an emotional or other connection between people: the relationship between teachers and students. 4. a sexual involvement; affair. relationship /rɪˈleɪʃənʃɪp/ noun 1. the state of being connected or related 2. association by blood or marriage; […]