On Oct 27, 4:35 pm, Thadeus Burgess <thade...@thadeusb.com> wrote:
> Ok, I was about to stand my ground, however I now agree with you.
>
> virtualfields is fine to me, as long as our DAL gets support for native SQL
> aggregates (liek SUM, AVG, etc).
The DAL does that already. Just not all of them.
It did so for one year. It is in the manual.
for row in db(...).select(db.table.field,db.table.otherfield.sum
(),groupby=db.table.field):
print row.table.field, row._extra[db.table.otherfield.sum()]
db.table.field.sum()
db.table.field.max()
db.table.field.min()
db.table.field.count()
> And when the DAL gets that, it leaves open the option to assign true aliases
> that are tied into the SQL query.
>
> aliases = {
> 'num_items': ['count', '*'],
> 'total_price': ['sum', 'item.price'],
> 'average_price': ['avg', 'item.price'],}
>
> db(db.invoice.id == request.vars.id_invoice).select(alias=aliases)
>
> So i'm okay with virtualfields now :P
>
> -Thadeus
>
> On Tue, Oct 27, 2009 at 4:12 PM, mdipierro <mdipie...@cs.depaul.edu> wrote:
>
> > No no. We are not doing that.
>
> > The new virtualfields are compute by web2py, not by the database.
>
> > Massimo
>
> > On Oct 27, 3:55 pm, Thadeus Burgess <thade...@thadeusb.com> wrote:
> > > Basically what we are doing is
>
> > > SELECT COUNT(*) AS "Number of Orders",
> > > SUM(quantity)AS "Total Number of Items Purchased",
> > > AVG(quantity)AS "Average Number of Items Purchased"
>
> > > FROM orders;
>
> > > What is the correct terminology for AS statement? Some research suggest
> > > ALIAS is the most accurate term.
>
> > > I think we should use "alias" or "aliases"
>
> > >http://www.w3schools.com/sql/sql_alias.asp
>
> > > -Thadeus
>
> > > On Tue, Oct 27, 2009 at 3:31 PM, mdipierro <mdipie...@cs.depaul.edu>
> > wrote:
>
> > > > I am going with "virtualfields"
>
> > > > On Oct 27, 3:19 pm, mdipierro <mdipie...@cs.depaul.edu> wrote:
> > > > > we normally user expressions to refer to things like this
>
> > > > > db(query).update(field=db.table.field+1)
>
> > > > > How about interface?
>
> > > > > On Oct 27, 3:05 pm, Thadeus Burgess <thade...@thadeusb.com> wrote:
>
> > > > > > Not meta, too confusing with django stuff.
>
> > > > > > How about expression, makes much more sense. That is what it is
> > > > actually
> > > > > > referred to when talking about SQL. Access calls them expressions
> > as
> > > > well.
>
> > > > > > -Thadeus
>
> > > > > > On Tue, Oct 27, 2009 at 2:32 PM, mdipierro <
> > mdipie...@cs.depaul.edu>
> > > > wrote:
>
> > > > > > > should this thing be called meta? interface? extension?
>
> > > > > > > On Oct 27, 2:26 pm, mdipierro <mdipie...@cs.depaul.edu> wrote:
> > > > > > > > Simple example:
>
> > > > > > > > db=DAL('sqlite://test')
> > > > > > > > db.define_table('purchase',
> > > > > > > > Field('item'),
> > > > > > > > Field('unit_price','double'),
> > > > > > > > Field('quantity','integer'))
> > > > > > > > db.purchase.insert(item='Box',unit_price=15,quantity=3)
> > > > > > > > rows=db().select(db.purchase.ALL)
>
> > > > > > > > class purchase_meta:
> > > > > > > > _tablename='purchase'
> > > > > > > > def __init__(self,tax):
> > > > > > > > self.tax=tax
> > > > > > > > def revenues(self):
> > > > > > > > return
> > > > > > > > self.purchase.unit_price*self.purchase.quantity*self.tax
>
> > > > > > > > rows.meta=purchase_meta(1.07)
>
> > > > > > > > for row in rows:
> > > > > > > > print row.item,
> > > > > > > > row.unit_price,'*',row.quantity,'*',row.tax,'=',row.revenues
>
> > > > > > > > More complex example:
>
> > > > > > > > db.define_table('a',Field('n','integer'))
> > > > > > > > db.define_table('b',Field('n','integer'),Field('a',db.a))
> > > > > > > > id = db.a.insert(n=4)
> > > > > > > > for i in range(3,5): db.b.insert(n=i,a=id)
> > > > > > > > rows=db(db.b.a==db.a.id).select() ### join
>
> > > > > > > > class products:
> > > > > > > > _tablename='c'
> > > > > > > > def n(self): return self.a.n*self.b.n
>
> > > > > > > > rows.meta=products()
> > > > > > > > for row in rows:
> > > > > > > > print row.a.n,'*',row.b.n,'=' row.c.n
>
> > > > > > > > Any suggestions on improving the syntax? Django can do the same
> > but
> > > > > > > > only at the level of the individual table. web2py can now to it
> > for
> > > > > > > > joins!
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