Hi David, Thanks for the reply. I realise there is no JOIN, hence the question.
Let's say I am converting an existing SQL-type app There are tables for Customer Order OrderLine Product and I need to extract all order lines for a customer for a particular product Acme Ltd - Order 123 - Quantity 24 - Desciption: Can Of Beer Acme Ltd - Order 132 - Quantity 12 - Desciption: Can Of BeerAcme Ltd - Order 155 - Quantity 48 - Desciption: Can Of Beer All this information is in different tables. You say to keep all the data duplicated in one place, which is OK, but what if Can Of Beer was a typo and needs to be changed to Can Of Lager? The real app will have many hundreds of thousands of records which will need to be updated and updating the status of a few hundreds of emails on GMail takes for ever Ian http://examples.roughian.com 2008/11/4 David Symonds <[EMAIL PROTECTED]> > > On Mon, Nov 3, 2008 at 9:07 PM, Ian Bambury <[EMAIL PROTECTED]> wrote: > > > I can't seem to find much on this which explains how to do anything more > > complicated that saving/returning a single entity. > > I've got a GWT app up and running on GAE, and I can save and retrieve > data > > no problem, but I need to be able to add the kind of functionality that > > JOINs let you do in SQL > > There is no such thing as JOINs for the datastore. You need to do what > is called "denormalisation", which is effectively duplicating data and > putting it everywhere you need it. > > > The customer has signed in and wants to see all outstanding orders for a > certain product. > > That doesn't sound like it needs a JOIN anyway. You'd get the current > customer ID, get that production ID, and them filter on the orders. > > If you flesh out your example a bit more, we can help you further. > > > Dave. > > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~----------~----~----~----~------~----~------~--~---
