- Relational Algebra is is a procedural query language
- The relational algebra provides a set of operations that take one or more relations as input and return a relation as an output.
- Practical query languages such as SQL are based on the relational algebra.
- The fundamental operations are
- Select, Project, Union, Set Difference, Cartesian Product and Rename.
- Additional to the fundamental operations are
- Intersection, join and assignment.
- he select, project and rename operations are called unary operations because they operate on one relation.
- The other operation which operate on pair of relations and are called binary operations.
- A basic expression in the relational algebra consists of either one of the following:
- A relation in the database
- A constant relation
- A constant relation is written by listing its tuples within { },
- Example { (22222, Einstein, Physics, 95000), (76543, Singh, Finance, 80000) }.
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