[Zope] setting null date in SQL

I cannot seem to set date to NULL in MS SQL with INSERT but it seems to work on UPDATE with this code: Insert sets date to 1/1/1900 <dtml-if "AppDelDate==''"> AppDelDate=NULL, <dtml-else> '<dtml-var name="AppDelDate" sql_quote>', </dtml-if> Trying this request to the group again since I have not found a solution. Sean