[Zope] silly DTML question: "in" test

I'm trying to do something in a DTML-Method (in ancient Zope 2.6.2) that seems like it should be really simple, but I can't get it right. I want to see if a value (defined via url-arg) is in a list which is generated from an RDBMS query (field type=integer). The pseudo-code would be something like: if foo in (select foo_col from table where x=y) then z='t' else z='f' I tried putting the simple SELECT query into a zSql and then calling it like: <dtml-call "REQUEST.set('foo_list',IfShowNextDoor())"> <dtml-if expr="foo in foo_list"> <dtml-call "REQUEST.set('z','t')"> <dtml-else> <dtml-call "REQUEST.set('z','f')"> </dtml-if> But that doesn't work.