- Relational calculus
Relational calculus consist of two calculi, the
tuple relational calculusand the domain relational calculus, that are part of the relational modelfor databases and provide a declarative way to specify database queries. This in contrast to the relational algebrawhich is also part of the relational model but provides a more procedural way for specifying queries.
The relational algebra might suggest these steps to retrieve the phone numbers and names of book stores that supply "Some Sample Book":
# Join books and titles over the BookstoreID.
# Restrict the result of that join to tuples for the book "Some Sample Book".
# Project the result of that restriction over StoreName and StorePhone.
The relational calculus would formulate a descriptive, declarative way:
:Get StoreName and StorePhone for supplies such that there exists a title BK with the same BookstoreID value and with a BookTitle value of "Some Sample Book".
The relational algebra and the relational calculus are essentially logically equivalent: for any algebraic expression, there is an equivalent expression in the calculus, and vice versa. This result is known as
The Third Manifesto
D (data language specification)
D4 (programming language)(an implementation of D)
Aldat Relational Algebra
Wikimedia Foundation. 2010.
Look at other dictionaries:
Tuple relational calculus — The tuple calculus is a calculus that was introduced by Edgar F. Codd as part of the relational model in order to give a declarative database query language for this data model. It formed the inspiration for the database query languages QUEL and… … Wikipedia
Domain relational calculus — In computer science, domain relational calculus (DRC) is a calculus that was introduced by Michel Lacroix and Alain Pirotte as a declarative database query language for the relational data model. In DRC, queries have the form: where each Xi is … Wikipedia
Calculus (disambiguation) — Calculus is Latin for pebble, and has a number of meanings in English: In mathematics and computer science Calculus , in its most general sense, is any method or system of calculation. To modern theoreticians the answer to the question what is a… … Wikipedia
Relational — may refer to: *Relational (mathematics) *Relational aggression *Relational algebra *Relational art *Relational database *Relational calculus *Relational operator *Relational model *Relational theory *Relational philosophy *Relational… … Wikipedia
Relational algebra — Not to be confused with Relation algebra. Relational algebra, an offshoot of first order logic (and of algebra of sets), deals with a set of finitary relations (see also relation (database)) that is closed under certain operators. These operators … Wikipedia
Relational database — A visual diagram showing the relationship between the two tables, as indicated by the arrow A relational database matches data by using common characteristics found within the data set. The resulting groups of data uses the relational model (a… … Wikipedia
Relational model — The relational model for database management is a database model based on first order predicate logic, first formulated and proposed in 1969 by Edgar Codd. [ Derivability, Redundancy, and Consistency of Relations Stored in Large Data Banks , E.F … Wikipedia
Calculus of predispositions — is a basic part of Predispositioning Theory and belongs to the indeterministic procedures. “The key component of any indeterministic procedure is the evaluation of a position. Since it is impossible to devise a deterministic chain linking the… … Wikipedia
Object-relational database — An object relational database (ORD), or object relational database management system (ORDBMS), is a database management system (DBMS) similar to a relational database, but with an object oriented database model: objects, classes and inheritance… … Wikipedia
Comparison of relational database management systems — Programming language comparisons General comparison Basic syntax Basic instructions Arrays Associative arrays String operations … Wikipedia