Converting a certain SQL query into relational algebra

Posted by Fumler on Stack Overflow See other posts from Stack Overflow or by Fumler
Published on 2012-09-15T15:29:30Z Indexed on 2012/09/15 15:37 UTC
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Filed under:

mysql

|

sql

|

database

|

query

|

relational-algebra

Just doing an assignment for my database course and I just want to double check that I've correctly wrapped my head around relational algebra.

The SQL query:

SELECT dato, SUM(pris*antall) AS total
FROM produkt, ordre
WHERE ordre.varenr = produkt.varenr
GROUP BY dato
HAVING total >= 10000

The relational algebra:

stotal >= 10000(
  ?R(dato, total)(
    sordre.varenr = produkt.varenr(
      datoISUM(pris*antall(produkt x ordre))))

Is this the correct way of doing it?

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