I am new to Database systems and I don't really have the best lecturer and we are learning about Relational algebra and relational calculus, not many videos or help online.

Please can someone assist me with this topic as i would like to get further knowledge

Answered by:- vikas_jk

A **query language** is a language in which user requests information from the database. it can be categorized as either
**procedural** or **nonprocedural.** In a procedural language the user instructs the system to do a sequence of operations on database to compute the desired result. In nonprocedural language the user describes the desired information without giving a specific procedure for obtaining that information.

The relational algebra is a procedural query language. It consists of a set of operations that take one or two relations as input and produces a new relation as output.

- SELECT
- PROJECT
- UNION
- SET DIFFERENCE
- CARTESIAN PRODUCT
- RENAME

Select and project operations are unary operation as they operate on a single relation.Union, set difference, Cartesian product and rename operations are binary operations as they operate on pairs of relations.

In contrast to Relational Algebra, Relational Calculus is a non-procedural query language, that is, it tells what to do but never explains how to do it.

Relational calculus exists in two forms -

Tuple Relational Calculus (TRC) :Filtering variable ranges over tuples

Domain Relational Calculus (DRC) : In DRC, the filtering variable uses the domain of attributes instead of entire tuple values.

As both of the above topics are quite big to cover here, I have just provided basic defination but here are some of the links which will help you to understand it more clearly.

https://www.w3schools.in/dbms/relational-calculus/

https://www.tutorialspoint.com/dbms/relational_algebra.htm

http://www.cs.sfu.ca/CourseCentral/354/lxwu/notes/chapter4.pdf

https://www.go4expert.com/articles/relational-algebra-operations-sql-t21166/

https://techdifferences.com/difference-between-relational-algebra-and-relational-calculus.html

**Practice questions**

https://courses.cs.washington.edu/courses/cse544/99sp/homeworks/sample/sample.html

https://pdfrog.com/download/relational_algebra_questions_with_solutions.pdf

http://www.edugrabs.com/relational-calculus/

The above links should clear your concept of Relational Algebra and Relational Calculus

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At:- 6/12/2018 6:52:21 AM
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