Hi
You really should start by thinking about the realized entities and
how they relate to each other at a
an application level rather than a sql table layout. Even think of it
as a high level Entity model in UML
before its transformed into a datamodel. Thats probably a closer
representation of how you will do it in app engine.
For instance (this is pseudo code ;-) so bits are missing and the not
valid syntax but you should get the idea.
class Customer:
name = stringproperty
address= stringproperty
class Premise:
ownedBy = referenceproperty(Customer)
address = stringproperty
class Person:
worksFor = referenceproperty(Customer):
locatedAt = referenceproperty(Premise)
So you would then do something like
c1 = Company()
c1.name = "company1"
c1.address = "1 somwhere road"
c1.put()
a1 = Premise()
a1.ownedBy = c1
a1.address = "2 somwhere else"
a1.put()
p1 = Person()
p1.worksFor = c1
p1.residesAt = a1
p1.put()
Have a read up on References that will help a lot
This looks a but like python which gives a good match between an
simple object model and how its implemented as datastore entities.
There are other ways of defining what you want especially in java that
look more table oriented, but you should try thinking about your data
as object graphs.
Hope this helps
T
On Mar 24, 7:08 am, RonBurgundy <sto...@googlemail.com> wrote:
> Hi,
>
> I am having real problems trying to understand the architecture of
> google app engine database as I am coming from SQL / Access database
> design. I have read all of your online documentation and watched
> various videos on you tube but still not sure how to design it.
>
> I am trying to replicate a simple db that I use onto google app
> engine:
>
> tblCustomer
> tblPremise
> tblPerson
>
> tblCustomer is the main table and will have details like company name
> and company address
> tblPremise links to the customer table such that 1 customer could have
> a number of premises, the premise table would hold info like address
> tblPerson links to both customer and premise such that all of the
> people are stored under customer but could be 1-1 relationship for
> premise
>
> Would it be possible to provide me with an understanding of how I
> would structure the db and link it together in the code please?
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