Re: how to solve this problem

Thank you very much!!!
your suggestion seems really usefull!! I will try it very soon!!!
ivan


Il giorno gio, 13/04/2006 alle 11.34 -0700, Steve Crawford ha scritto:
> > I have a table where there are 20 columns named
> > vinc1, vinc2, vinc3, vinc4, etc....
> > 
> > the values contained into each column are simply 1 or 0  (each column is
> > dichotomic)
> > 1 means presence
> > 0 means absence
> > 
> > I would obtain a column (new_column) containg the name of the columns,
> > comma separated, where the value is = 1
> > 
> > for example:
> > 
> > vinc1    vinc2    vinc3    vinc4    new_column
> > 1    0    1    0    vinc1,vinc3
> > 0    0    0    1    vinc4
> > 0    1    1    1    vinc2,vinc3,vinc4
> > 
> > can someone help me to find the best way to obtain this result???
> > thank you very much
> 
> Here's a brute-force method. Maybe someone else has a more elegant way. 
> More info on the nature of your data and what you are trying to obtain 
> from it would help in finding such elegance.
> 
> select
>    substr(
>    case when vinc1 = 1 then ',vinc1' else '' ||
>    case when vinc2 = 1 then ',vinc2' else '' ||
>    ...
>    case when vinc20 = 1 then ',vinc20' else ''
>    ,2) as new_column ...
> 
> As to the binary representation mentioned elsewhere, the idea is that 
> you can view vinc1-vinc20 as bits in a binary number equal to vinc1 + 
> 2*vinc2 + 4*vinc3 + 8*vinc4...2^19*vinc20. Whether or not this is useful 
> depends on what you are trying to do.
> 
> Cheers,
> Steve
> 
-- 
Ivan Marchesini
Department of Civil and Environmental Engineering
University of Perugia
Via G. Duranti 93/a 
06125
Perugia (Italy)
e-mail: marchesini@unipg.it       ivan.marchesini@gmail.com
tel: +39(0)755853760
fax: +39(0)755853756
jabber: geoivan73@jabber.org