Could you use the python 'operator' module
(http://docs.python.org/library/operator.html)?
Eg. (untested):
import operator
operations = {
'+': operator.add,
'-': operator.sub,
# etc.
}
def combine_columns(op, *cols):
return operations[op](*cols)
sum_column = combine_columns('+', a, b)
I think that should work.
Simon
> -----Original Message-----
> From: sqlalchemy@googlegroups.com
> [mailto:sqlalch...@googlegroups.com] On Behalf Of Ashish Bhatia
> Sent: 25 February 2009 13:26
> To: sqlalchemy
> Subject: [sqlalchemy] Re: Creating SQL Expression
>
>
> The problem is still their.
>
> The two seprate list of
> columns = List of sqlalchem object
> operator = ['+'','-']
>
> using join to join them will convert the columns object to string
> which is not desirable.
>
> Any way to fix this.
>
> On Feb 25, 3:54 pm, Ashish Bhatia <ashishsinghbha...@gmail.com> wrote:
> > sorry its resolved and working
> >
> > On Feb 25, 12:20 pm, Ash <ashishsinghbha...@gmail.com> wrote:
> >
> > > Hello ,
> >
> > > I am trying to make query like
> >
> > > select (a+b) from xyz;
> >
> > > to do this
> >
> > > xyz = sqlalchemy.Table('xyz',metadata)
> >
> > > a = sqlalchemy.Column('a', sqlalchemy.Integer)
> > > xyz.append_column(a)
> > > b = sqlalchemy.Column('b', sqlalchemy.Integer)
> > > xyz.append_column(b)
> >
> > > column = [(a + b)]
> > > select = sqlalchemy.select(from_obj=xyz,
> columns=column,distinct=True)
> >
> > > This works fine for me.
> >
> > > Now when the columns a and b are dynamic (Enter by the
> user in form of
> > > string) and the operator too comes from user
> >
> > > columns_list = ['a','b']
> > > operator = ['+']
> >
> > > like this i get the input
> >
> > > so i make the loop and make
> >
> > > for both the columns something like this
> > > columns = []
> > > for x in column_list :
> > > t = sqlalchemy.Column(x, sqlalchemy.Integer)
> > > xyz.append_column(a)
> > > columns.append(t)
> >
> > > so now
> > > how to add + to make the quer run
> >
> > > Thanks in the advance.
> >
>
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