Calculating Age of two different posting dates

Hi All,

I have to create a query in which I need to display the number of days between 'Purchase Order Posting Date' and 'Invoice Posting date'.

Let me explain this better with an example:-

I have 'Purchase Order Posting Date'(PO Date) and 'Invoice Posting Date'(Inv Date), now say I have PO Date as 12/21/2005 and Inv Date as 1/18/2006. I need to show also a third column which shows the number of days between these two posting dates.

<i>PO Date</i>---- <i>Inv Date</i> -<i>PO/INV</i> (calendar days)

<i>12/21/2005</i> -<i>1/18/2006</i> --<i>28</i>

I hope the question is now clear.

Any help in this regard will be appreciated.

Thanks & Rgds,

M