Last not null value from previous rows

From: Shakespeare <whatsin_at_xs4all.nl>
Date: Tue, 26 Jan 2010 20:48:39 +0100
Message-ID: <4b5f4717$0$22934$e4fe514c_at_news.xs4all.nl>

I vaguely remember this has been asked and answered before, but can not find the answer anymore:
Suppose I have a table in which a column has a value for some rows, and none (null) for others. Is there a way to let a select statement (which returns values from the current row) return the last non null value for this column? So, in pseudo code:

select

   col1,
   col2,
   "last-non-null value for col3"
from a_table
order by col1?

Thanks in advance,

Shakespeare Received on Tue Jan 26 2010 - 13:48:39 CST