Hi everyone
Consider there are three tables book,money,card in database.
Book has got column names name,price.
Money has got column names price,type.
Card has got column names type,id.
Now based on the ''id'' of the ''card''
i''ve to fetch ''name'' of the ''book''.
So i m writing a query in RoR model as
Book.find(:all, :select => "book.name",
:joins => "INNER JOIN money ON money.price
book.price"+
"INNER JOIN card ON card.type = money.type",
:conditions => "`card`.`id` =
''10''")
But this doesnt work.Is there any alternate query or i m missing
something in this query.
Any help would be appreciated.
Thanks in advance
Anandh
--
Posted via http://www.ruby-forum.com/.
Well, I don''t know the answer, but you can probably use the sql query mentioned in this page: http://www.keithjbrown.co.uk/vworks/mysql/mysql_p5.php ( Do a browser search on string "Joining Three Tables") BTW, this email is to mention a different problem in your query: should not card be cards and book be books in your query (table names are, by convention, plural in rails) Try that too, might work. Thanks, Abhinav -- अभिनव http://twitter.com/abhinav On Tue, Sep 8, 2009 at 10:55 AM, Anandh Kumar < rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote:> > > > Hi everyone > > Consider there are three tables book,money,card in database. > > Book has got column names name,price. > > Money has got column names price,type. > > Card has got column names type,id. > > Now based on the ''id'' of the ''card'' i''ve to fetch ''name'' of the ''book''. > > So i m writing a query in RoR model as > > > > Book.find(:all, :select => "book.name", > :joins => "INNER JOIN money ON money.price > book.price"+ > "INNER JOIN card ON card.type = money.type", > :conditions => "`card`.`id` = ''10''") > > > But this doesnt work.Is there any alternate query or i m missing > something in this query. > > Any help would be appreciated. > > Thanks in advance > > Anandh > -- > Posted via http://www.ruby-forum.com/. > > >--~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe@googlegroups.com For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
2009/9/8 Anandh Kumar <rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>:> > > > Hi everyone > > Consider there are three tables book,money,card in database. > > Book has got column names name,price. > > Money has got column names price,type. > > Card has got column names type,id. > > Now based on the ''id'' of the ''card'' i''ve to fetch ''name'' of the ''book''. > > So i m writing a query in RoR model as > > > > Book.find(:all, :select => "book.name", > :joins => "INNER JOIN money ON money.price > book.price"+ > "INNER JOIN card ON card.type = money.type", > :conditions => "`card`.`id` = ''10''") > > > But this doesnt work.Is there any alternate query or i m missing > something in this query.Don''t use a column called type, it is a reserved word in rails as it is used in Single Table Inheritance. There are workarounds but much better not to use it if possible. You have not told us what are the relationships between the models. If you set these up appropriately rails will almost always generate the joins for you. If you have to specify joins explicitly then possibly you have not set your relationships up correctly. Colin