# Relational algebra

May 29th, 2015
Studypool Tutor
Price: \$10 USD

Tutor description

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 operate on one or more relations to yield a

Word Count: 4128
Showing Page: 1/11
Relational algebra, an offshoot offirst-order logic(and ofalgebra of sets), deals with a set offinitary relations(see alsorelation (database)) that isclosedunder certainoperators. These operators operate on one or more relations to yield a relation.Relational algebra is a part ofcomputer science.Relational algebra received little attention outside of pure mathematics until the publication ofE.F. Codd'srelational model of datain 1970. Codd proposed such an algebra as a basis for database query languages. (See sectionImplementations.)Relational algebra is essentially equivalent in expressive power torelational calculus(and thusfirst-order logic); this result is known as Codd's theorem. You must be careful to avoid a mismatch, that may arise between the two languages since negation, applied to a formula of the calculus, constructs a formula that may be true on an infinite set of possibletuples, while the difference operator of relational algebra always returns a finite result. To overcome these difficulties, Codd restricted the operands of relational algebra to finite relationsonly and also proposed restricted support for negation (NOT) and disjunction (OR). Analogous restrictions are found in many other logic-based computer languages. Codd defined the termrelational completenessto refer to a language that is complete with respect to first-order predicate calculus apart from the restrictions he proposed. In practice the restriction

## Review from student

Studypool Student
" Excellent work as always thanks so much "

1831 tutors are online

Brown University

1271 Tutors

California Institute of Technology

2131 Tutors

Carnegie Mellon University

982 Tutors

Columbia University

1256 Tutors

Dartmouth University

2113 Tutors

Emory University

2279 Tutors

Harvard University

599 Tutors

Massachusetts Institute of Technology

2319 Tutors

New York University

1645 Tutors

Notre Dam University

1911 Tutors

Oklahoma University

2122 Tutors

Pennsylvania State University

932 Tutors

Princeton University

1211 Tutors

Stanford University

983 Tutors

University of California

1282 Tutors

Oxford University

123 Tutors

Yale University

2325 Tutors