August 2009
Intermediate to advanced
893 pages
26h 48m
English
Content preview from Database Systems: Concepts, Design and Applications
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4.4. Relational Algebra
Relational algebra is a collection of operations to manipulate or access relations. It is a procedural (or abstract) language with operations that is performed on one or more existing relations to derive result (another) relations without changing the original relation(s). Furthermore, relational algebra defines the complete scheme for each of the result relations. Relational algebra consists of set of relational operators. Each operator has one or more relations as its input and produces a relation as its output. Thus, both the operands and the results are relations and so the output from one operation can become the input to another operation.
The relational algebra is a relation-at-a-time (or set) language in which ...