>> In an relational database setting you would have a table for artists, >> a table for cd's and a table for songs and a table for comments where >> people can comment on songs. All of this with obvious foreign keys. >> Now you want to display on your website the total number of cd's, the >> total number of songs and the total number of comments because that >> looks very cool on top of every page: 1242342 cd's and 134242342342 >> songs and 284284728347284728 comments! >> >> Okay, so you need to issue a query with joins in your relational db. >> Or in another query, you want to select all comments of an artist, >> meaning all comments that were comments on a song belonging to cd's of >> a given artist. This would also involve joins. >> >> How would I do these queries if I can't have joins or in other words >> how would I lay out my data storage? >> >> Thanks by the way for your help and replies, >> Daniel >> > > What actually is happening here is that feature x which is usually in an > abstraction layer (like a RDBM) is not available to you. Which means you > have to write code which does the same but on your side of the code. > > I played a bit around with the GAE some time ago and designed the > storage of all data in an sort of EAV model > (http://en.wikipedia.org/wiki/Entity-Attribute-Value_model) > The abstraction layer had all my meta code, counting stuff up was a > matter of creating a list of id's from one section and with that list > selecting the appropriate records on the other section, then count up > the number of results or use the result again, it is very likely you > have to do quite a lot of queries before you get the result. > > So in other words, just lay out the data which makes the most sense to > you, the pain of recreating SQL like logic is there no matter what > layout you choose.
Thanks, this wikipedia entry was actually very useful as well as your other comments. Thanks again, Daniel -- Psss, psss, put it down! - http://www.cafepress.com/putitdown -- http://mail.python.org/mailman/listinfo/python-list
