[Zope] zsql method question

[Laura McCord]

I am trying to do an insert but I do not want the insert to occur if the
value of "ipAddress" was not entered in the form.

So far I have this:

insert into NetInt(IPAddress, SystemNetName)
Values(
'<dtml-var name="ipAddress" sql_quote>',
'<dtml-var name="HostName" sql_quote>'
)

I am thinking that I have to put a conditional statement such as 
<dtml-if ipAddress>
 insert into NetInt(IPAddress, SystemNetName)
Values(
'<dtml-var name="ipAddress" sql_quote>',
'<dtml-var name="HostName" sql_quote>'
)
</dtml-if>

Any suggestions?

Thanks,
 Laura