[Zope] Is there a <dtml-comma> for SQL UPDATEs?

[David Salgado]

>Hmmm.... AFAIK, there's no such animal as <dtml-comma>.  But without
>much research on the matter, I'd say that this'd do it:
>
>UPDATE
>  users
>SET
>  <dtml-sqlgroup>
>    <dtml-sqltest login type=nb optional>
>    <dtml-if email>,<dtml-sqltest email type=nb optional></dtml-if>
>  </dtml-sqlgroup>
>WHERE
>  <dtml-sqltest userid type=int>
>

Any ideas on how to do this without hard-coding the field names into the
ZSQL method? I'm trying to use a property which defines a list of fields,
and then my editing/listing interface can be generic for a whole bunch of
record types, acquiring the list of fields to decide what to display/update.

Actually, I guess my question boils down to 'how do I remove a trailing
comma from a string in a ZSQL method?' -- any ideas?

Cheers
          David