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mysqlsqldatabasegroup-byrelational-algebra

Equivalent of GroupBy and Having clause in Relational Algebra

I was doing an assignment where I had to convert SQL queries into Relational Algebra queries. I got stuck in converting the group by clause.

Could anyone please tell me how the group by clause can be written in relational algebra?

e.g.:

SELECT job, sal 
  FROM emp
 GROUP BY job
       ;

Thanks!

Solution

  • First of all your query is wrong you cannot select something that you did not group unless you use aggregation. I assume you want to get sum of the sal.

    job F sum(sal), job(emp).