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. ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ sqlobject-discuss mailing list sqlobject-discuss@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sqlobject-discuss