[postmodern-devel] Query generation

[Osei Poku]

On Wed, Jun 27, 2007 at 09:24:44PM +0200, Ralf Mattes wrote:
> On Wed, 2007-06-27 at 21:22 +0200, Ralf Mattes wrote:
> > On Wed, 2007-06-27 at 14:29 -0400, Osei Poku wrote:
> > > Hi,
> > > 
> > > I want to generate the following query:
> > > 
> > > "UPDATE table1 SET col1 = NULL, col2 = NULL"
> > > 
> > > from the following list: ("col1" "col2")
> > > 
> > > my attempt is:
> > > 
> > > (sql
> > >    (append
> > >       '(:update :table1 :set)
> > >       (loop for a in '("col1" "col2")
> > >             collect a collect :NULL)))
> > > 
> > > but that apparently doesnt work.  this can probably be attributed to
> > > my newness to lisp.
> > > 
> > > Any ideas?
> > 
> > 'postmodern:sql' is a macro, not a function and hence will not evaluate
> > its argument. When your code really looks like above you could fix it
> > like this:
> > 
> > (sql #.(append
> >        '(:update :table1 :set)
> >         (loop for a in '("col1" "col2")
> >             collect a collect :NULL)))
> > 
>

Aah, the beauty of the obscure and powerful reader macro :)  This is
pretty much what I thought I needed until ...

> 
> Sorry for following up my own post: if you really need to build up your
> SQL at runtime you could also use the functional pendant to 'sql':
> 
>  (sql-compile(append
>        '(:update :table1 :set)
>         (loop for a in '("col1" "col2")
>             collect a collect :NULL)))
> 
>

Yes. This is what I really want:  the ability to freely insert
arbitrary s-exps in the s-sql syntax.  The two solutions are probably
equivalent anyway.

Thanks a bunch.

> Cheers, RalfD
> 
> > 
> > 
> >  
> > >  thanks
> > > 
> > 
> > _______________________________________________
> > postmodern-devel mailing list
> > postmodern-devel at common-lisp.net
> > http://common-lisp.net/cgi-bin/mailman/listinfo/postmodern-devel
> 
> _______________________________________________
> postmodern-devel mailing list
> postmodern-devel at common-lisp.net
> http://common-lisp.net/cgi-bin/mailman/listinfo/postmodern-devel

-- 
Osei Poku
PhD Student, ECE
Carnegie Mellon University