Will the following work?
UPDATE child SET child_name = (SELECT parent_name FROM parent WHERE
parent_id = child_parent_id) WHERE child_name = 'not known' ;
That is, copy the parent_name into the corresponding child_name if the
child_name was 'not known'
Michael Rowan
mike.rowan@internode.on.net
11 Kingscote Street
ALBERTON
South Australia 5014
tel 618 8240 3993