Tom Evans wrote: > Phlip, I'm going to try and make a non-stupid comment now :)
http://xkcd.com/386/ > If you already know precisely the query you want to use, and you can't > coerce django's ORM to produce it, can you simply use Manager.raw()[1] > to generate the result set you are after? Because the point of an ORM is to distribute declarations of relations among objects, so each object adds details to a query set, and the ORM can build the final SELECT statements for each context. So anyway, here's a table (hand-censored - it's a blue-sky project in a hyper-competitive space): > select * from things; +-----+-----------------+ | pid | name | +-----+-----------------+ | 6 | soca_2k7_user | | 7 | isabelle_item | | 8 | max_item | | 9 | isabelle_item | +-----+-----------------+ Note that "isabelle_item" appears twice. We are following the auditing rule "always write new records to change data - never edit previous records". Someone edited isabelle_item's payload data (not shown), so we add a new record without touching the existing record. This implies that all normal database queries should only look at the "top level horizon" of the database. (And this implies we must mix-and- match such queries, and they can't all rely on the order_by('-pk')[0] trick.) So this statement correctly fetches only the latest items: SELECT a.* FROM things a WHERE a.pid in (select max(b.pid) from content_entity b group by b.name) Now I thought (from my allegedly copious experience with SQL) that I could do it with a join-on-self, but I can't seem to get the SQL syntax right. And if I did, I would then not know how to ORM-ize that syntax (and yes it must be ORM-ized, because this is indeed the core of the project, and everything has to see top-level horizons. Except auditors). -- Phlip http://zeekland.zeroplayer.com/ -- You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-us...@googlegroups.com. To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/django-users?hl=en.
