• Post Reply Bookmark Topic Watch Topic
  • New Topic
programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other Pie Elite all forums
this forum made possible by our volunteer staff, including ...
Marshals:
  • Campbell Ritchie
  • Jeanne Boyarsky
  • Ron McLeod
  • Paul Clapham
  • Liutauras Vilda
Sheriffs:
  • paul wheaton
  • Rob Spoor
  • Devaka Cooray
Saloon Keepers:
  • Stephan van Hulst
  • Tim Holloway
  • Carey Brown
  • Frits Walraven
  • Tim Moores
Bartenders:
  • Mikalai Zaikin

Enthuware say's this as a Cartesian Join

 
Ranch Hand
Posts: 856
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator

SELECT s.name FROM Student s, Program p where s.subjectid=p.subjectid

An inner join may be implicitly specified by the use of a cartesian product in the FROM clause and a join condition in the WHERE clause. In the absence of a join condition, this reduces to the cartesian product.
The main use case for this generalized style of join is when a join condition does not involve a foreign key relationship that is mapped to an entity relationship.

Example:
select c from Customer c, Employee e where c.hatsize = e.shoesize

In general, use of this style of inner join (also referred to as theta-join) is less typical than explicitly defined joins over entity relationships.



this given query does not qualify for cartesian join because there is relationship defined between them although join not being used here.
 
And inside of my fortune cookie was this tiny ad:
a bit of art, as a gift, the permaculture playing cards
https://gardener-gift.com
reply
    Bookmark Topic Watch Topic
  • New Topic