On Aug 12, 2011, at 6:43 PM, nospam wrote:
> I'm trying to do something like this in sqlalchemy:
>
> select (score/10)*10 || '-' || (score/10)*10+9 as scorerange,
> count(*)from scoresgroup by score/10 order by 1
>
> which should give:
> scorerange | count
> ------------+-------
> 0-9 | 11
> 10-19 | 14
> 20-29 | 3
> 30-39 | 2
>
> Any ideas on how to do the string concatentation in the ranges?
the + operator resolves to the concatenation operator if used against an
expression with a string type, or if using untyped elements concat() will get
you there:
from sqlalchemy.sql import column
column('foo', String) + "bar"
column('foo').concat("bar")
your expression above appears to be evaluating a numeric against a string
(so...this is MySQL ? :) ) you might consider calling cast(expr, String) on
the numeric value before evaluating in a string context.
((score / 10) * 10).concat("-").concat((score / 10)*10) + 9).label('scorerange')
from sqlalchemy import cast, String
cast((score / 10) * 10, String).concat("-").concat(cast((score / 10)*10) + 9,
String)).label('scorerange')
>
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