[Zope] zsql-Methods: how to make a dynamic where-clause?

Hi, is there any convenient way, to have a dynamic where-clause in zsql-Methods? All my effords had severe limitation up to now: 1. <dtml-sqltest .. needs a fixed column=.... expression 2. WHERE <dtml-var ...> with the whole clause in the var doesn't work because of quoting problems. ... So it seems that there is only very limited scope with <sql-group and explicit column=myExplicitColumnName constructs or am I missing something? A completely dynamic query with python script would be also a good alternative but how to do that? -- thanks for any input, Elena