Hi JCC,
I think your parameter construction is wrong. You're telling Zope that a list is a string, and furthermore, to iterate over a string, which won't work.
In the ZSQLGuide I've got it says that ids:list:int indicates that ids is a list of integers. So columns:list:string should mean that columns is a list of strings. But even columns:list didn't work. After further investigation I think the parameter-parsing of zsql-methods is quite restricted and it's better to pass "complicated" structures via a single dictionary. I'll try that. But still I would like to know how it would work with lists and dtml_in constructs. Anyway some complete examples including the parameter part would enhance the ZSQLGuide a lot. -- anyway thanks for your answer, Elena