Please respond to the following discussion below with 150 words


Please respond to the following discussion below with 150 words or more relating to relational algebra and its relation to SQL.

 

As a collection of algebraic structures, relational algebra was  developed at IBM by Edgar F. Codd. It is used to represent data stored  in relational databases, as well as to define queries on that data. An  instance of relational algebra may be described as a procedural query  language that employs unary or binary operators to execute queries.  Users of relational database systems must be able to query database  instances using a query language. Relational algebra or relational  calculus is used to query a relational database system. Recursive  relational algebra is done on a relation, and intermediate outcomes are  also considered relations. For Edgar F. Codd’s relational paradigm, SQL  was one of the first commercially available programming languages.  Despite the fact that they are based on similar principles, their syntax  differs. There are several advantages to relational algebra, including  its closed nature, rigorous basis, and simplicity of semantics. SQL, on  the other hand, is a subset of relational algebra with easy formatting  capabilities, aggregate functions, and a complex semantics. Below is an  example from the course readings that illustrate the difference in  syntax:

SELECT DISTINCT dname
FROM department, course, empcourse, employee WHERE cname = `Further Accounting’

AND course.courseno = empcourse.courseno AND empcourse.empno = employee.empno AND employee.depno = department.depno;

The equivalent relational algebra is

PROJECTdname (department JOINdepno = depno ( PROJECTdepno (employee JOINempno = empno (

PROJECTempno (empcourse JOINcourseno = courseno ( PROJECTcourseno (SELECTcname = `Further Accounting’ course)

)) ))

))

References:

Relational algebra – example. (n.d.). https://web.archive.org/web/20160326123806/http:/db.grussell.org/section011.html.

Relational algebra. (n.d.). https://www.tutorialspoint.com/dbms/relational_algebra.htm.

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