Relation algebra

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

Tutor description

Relation algebra consists of a set of operations that take one or two relations as input and produce a new relation as their results.Relatin algebra is procedural language

Word Count: 1245
Showing Page: 1/12
Relation algebraRelation algebra consists of a set of operations that take one or two relations as input and produce a new relation as their results.Relatin algebra is procedural languageSix basic operatorsselect: s project: union: set difference: Cartesian product: xrename: r Fundamental RelationalThe select,project And rename operations are called unary operations,because they operate on one relation.The other set difference,Cartesian product,union are operate on pairs of relations and are therefore called binary operations.Unary OperationsThe Select OperationsThe select operations select tuples that satisfy a given predicate.Select is denoted by lowercase Greek letter sigma(s ),with the predicate appearing as a subscriptNotation-s p(r)Example-To select those tuples of the relation Employee whose city is Mumbai.scity=Mumbai (Employee)We combine several predicates into a larger predicates by using the connectives (and), (or), (not)Example- To select those tuples of the relation Employee whose city is Mumbai and empid is 10scity=Mumbai empid=10 (Employee)The Project OperationsThe project operation is a unary operation that returns its argument relation,with certain attributes left out.Project is denoted by lowercase Greek letter pi()We list those attributes that we wish to appear in the result as a subscript to Notation-attribute1,attribute2attributen(Relation)Example-To list only

Review from student

Studypool Student
" AMAZING as always! "
Ask your homework questions. Receive quality answers!

Type your question here (or upload an image)

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