What were you afraid it was going to do? Perhaps this?
$node= '"; delete from nodes; ...';
Go ahead and try it (with something less dangerous). It doesn't work for me as I can't put multiple statements in a single DBI prepare().
I'm not defending code like that, I'm just pointing out something that I've always been told was a horrid security risk ("They could do anything they wanted to your data!") that isn't as bad (AFAICT) as lots of people are making it out to be.
Sure, they could probably launch a denial of service attack by making your SELECT extremely complicated if they could guess some of the structure of your database. (:
(but my friends call me "Tye")