need help with expression

[safam]

can any one please give me an expression, what i am trying to achieve is:
KPI=[DeliveryDate]-[SubDate]

if [DeliveryDate]IS NULL, Date()-[SubDate] OR [DeliveryDate]-[SubDate]

 

[pr2-eugin]

Is this in a Query?

KPI = Nz([DeliveryDate], Date()) -[SubDate]

 

[safam]

sorry i forgot to mention.
this is a code i am running on a form.

 

[vbaInet]

You had the idea so you could have looked up the IIF() function:

IIF(IsNull([DeliveryDate]), Date()-[SubDate], [DeliveryDate]-[SubDate])

 

[safam]

thanks,vbaInet. works like a charm.

thanks for the quick response guys.