update with multi table join

From: Ken Chesak <datavector_at_hotmail.com>
Date: 6 Nov 2003 13:16:06 -0800
Message-ID: <3f2f39c4.0311061316.78f840b5@posting.google.com>

When the subquery finds nothing the id_bjn is updated with null. How can I avoid updating records when there is no match is found in the subquery?

update w_rg101 w
set id_bjn = ( select c.id_destination from bjn a, bjn_destination c

			where w.id_region_tw = a.id_region
			and w.id_unit_tw = a.id_unit
			and w.id_mail_tw = a.id_mail)

where cd_source <> 'ITSI' and id_bjn is null; Received on Thu Nov 06 2003 - 15:16:06 CST