Return value of prev record if null in query

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From: Laura (anonymous_at_discussions.microsoft.com)
Date: 09/24/04 

Date: Fri, 24 Sep 2004 08:53:15 -0700

I would like to develop a query to return a value of the
previous record if the next record's value is blank.

Example:

Record1 application_id=1.
Record2 application_id=" ".

If application_id=" " application_id=previous record's
application_id.

Any idea of how to write that in SQL or in query format?
Thx.