On Thu, Feb 07, 2008 at 01:18:33PM -0600, Christopher Singley wrote:
> > I mean "dynamical system" where the state of the system is a function of
> > time. I need a function which accepts a time variable as an input, and
> > returns a state.
> >
> > Consider exchange-traded securities (e.g. stocks). An important attribute
> > of a stock is its price. Stock trading prices are a time series of
> > discrete points. Yahoo Finance, among others, persists series of prices
> > and allows users to look them up by time. That's the kind of thing I'm
> > talking about:
>
> So then:
> class SecurityState(SQLObject):
> parent = ForeignKey('Security')
> date = DateCol()
> price = DecimalCol(size=10, precision=4)
>
> class Security(SQLObject):
> states = MultipleJoin('SecurityState', joinColumn='parent_id')
>
> Why define a separate class for security? So that Security.id can be used as
> a foreign key in other tables. For example:
>
> class SecurityTransaction(SQLObject):
> time = DateTimeCol()
> price = DecimalCol(size=10, precision=4)
> security = ForeignKey('Security')
>
> Is there a better way of representing data like this in SQL/SQLObject?
I don't think so, and I think you scheme is very good for the task.
Oleg.
--
Oleg Broytmann http://phd.pp.ru/ [EMAIL PROTECTED]
Programmers don't die, they just GOSUB without RETURN.
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