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