The distinction between relational calculus and relational algebra is that relational calculus is a declarative language, while relational algebra is a procedural language.
In a declarative language like relational calculus, the user specifies what they want to retrieve from the database, without specifying how to retrieve it. The user provides a logical statement that describes the desired results, and the system uses this statement to generate the necessary code to retrieve the results. Relational calculus is based on predicate logic, and it provides a way to specify queries in terms of logical predicates that define the desired properties of the result set.
In contrast, relational algebra is a procedural language that specifies how to retrieve the desired results from the database. The user provides a sequence of operations to be performed on the relations to produce the desired result set. Relational algebra provides a set of operators such as select, project, join, union, and intersection, which can be combined to perform complex queries.
The main advantage of a declarative language like relational calculus is that it allows the user to focus on what they want to retrieve, rather than how to retrieve it. This makes it easier to express complex queries, and it enables the database system to optimize the retrieval process, based on the logical statement provided by the user.
In contrast, the main advantage of a procedural language like relational algebra is that it provides precise control over the retrieval process, which can be important in certain situations. For example, a procedural language can be used to optimize the retrieval process based on specific performance considerations, or to specify a sequence of steps that must be followed in a particular order.
In summary, the distinction between relational calculus and relational algebra is that relational calculus is a declarative language that focuses on what to retrieve, while relational algebra is a procedural language that focuses on how to retrieve it.
