Thanx, i ll try using a view, if i understood i ll have to create a view and
join this view with my products table in each query, is that it?

On 9/13/06, Adam <s3057043@...> wrote:
>
> --- In firebird-support@yahoogroups.com<firebird-support%40yahoogroups.com>,
> "Fabio Gomes" <fabioxgn@...>
>
> wrote:
> >
> > Hi guys,
> >
> > I have another question :)
> >
> > The solution using SUM() and a table with quantitys is working fine
> now, but
> > i have another doubt.
> >
> > I have my products table:
> >
> > product_id
> > description
> > quantity
> >
> > This quantity, is the sum of all the records of the product in the other
> > table, wich would be the best way to keep it updated?
> >
> > Should i use a query with a join and SUM() each time i need to see the
> > quantity?
> >
> > Or sould i create a view? or maybe a computed field (i dont have any
> idea
> > how it works btw)? Or can i even use a trigger?
> >
> > Which would be the best way to do it?
>
> I would create a view called GetCount or something like that. The
> summing mechanism you are using works really well, but it is not very
> intuitive when included in a query.
>
> With a view, it looks much more obvious what you are doing, and you
> can use the view inside the SP as well, simply join to the view on
> (1=1) to get the count for each record.
>
> My personal experience with computed fields has been that they tend to
> have performance problems when they involve records other than the
> current one. Great for getting the difference between income and
> expenses without having to use a specific field for it, but not much
> good when you have to join.
>
> I don't think you would want to try to use a trigger. The time saved
> by not having to perform your count would be swallowed by the time it
> took to update all the records to store the count.
>
> Adam
>
>
>


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