OK here's an example of counting matching records with web2py syntax.
SQL version
select count(*) from tbbooks where id = 1 group by id;
Note! if you don't add the GROUP BY clause, you'll get a count
of 1 record... even if there a NO MATCHES.... probably NOT what you intended
to do.
The GROUP BY clause give you an "Empty Set" for non-matching search results
web2py version
matches = db(db.tbbooks.id == 1).count()
On Wed, May 26, 2010 at 2:44 PM, scausten <scaus...@googlemail.com> wrote:
> I'm adding files content to my database with the following code being
> called onvalidation when the form is submitted. It really simply
> generates a 6-digit alphanumeric code as an identifier for the file:
>
> codes = db().select(db.products.code) # Grabs all the existing codes
> from the database
> while not form.vars.code:
> code = "".join([random.sample(string.ascii_lowercase
> +string.digits, 1)[0] for i in range(6)]) # Creates a code
> if not code in codes: # If its unique...
> form.vars.code = code # ...add it into the form vars
>
> It works fine at the moment, but I'm hoping to have several hundred
> thousand files potentially, and I'm worried that the database call to
> pull all existing codes will become a serious bottleneck. The code
> needs to be random and not sequential.
>
> Does anyone have any ideas on how I can do this more elegantly?
>
