Strange output from list

[John Machin]

On Nov 11, 10:47 pm, Steve Holden <st... at holdenweb.com> wrote:
> Chris Rebert wrote:
> > On Tue, Nov 11, 2008 at 12:56 AM, Gilles Ganault <nos... at nospam.com> wrote:
> >> On Mon, 10 Nov 2008 20:02:39 -0600, Andrew <alif... at gmail.com> wrote:
> >>> sql = 'SELECT id FROM master'
> >>> rows=list(cursor.execute(sql))
> >>> for id in rows:
> >>>       sql = 'SELECT COUNT(code) FROM companies WHERE code="%s"' % id[0]
> >>>       result = list(cursor.execute(sql))
> >>>       print "Code=%s, number=%s" % (id[0],result[0][0])
>
> > Using liberal "term rewriting", consider the following rough
> > equivalencies in the code:
>
> > id[0] <==> rows[INDEX_HERE][0] <==> list(cursor.execute(sql))[INDEX_HERE][0]
> > result[0][0] <==> list(cursor.execute(sql))[0][0]
>
> > Note that in both cases, the list is sliced twice; the for-loop just
> > conceals the `[INDEX_HERE]` implicit slicing that is caused by
> > iterating over the list.
>
> You might also want to consider saving some time by using a SQL solution
> (assuming SQLite supports it, which it should) (untested):
>
> cursor.execute("""
> SELECT master.id, count(companies.code)
>    FROM master JOIN companies ON master.id = companies.code
>    GROUP BY companies.code""")

Shouldn't it be GROUP BY master.id? I would have thought that SQL
would be sad about a non-aggregate (master.id) that's in the SELECT
list but not also in the GROUP BY list.

> for id, count in cursor.fetchall():
>    print "Code=%s, number=%s" % (id, count)
>
> I'd like to think it makes the Python a bit more readable too ...

Agreed. result[0][0] is an abomination.