$STI = $DB->prepare('insert into foo (a, b) values (a, b)'); $STS = $DB->prepare('select a, b from bar'); $STS->execute(); while (my $ar = $STS->fetchrow_arrayref()) { $ar->[1] = defined($ar->[1]) ? $ar->[1] : '=null='; $STI->execute(@$ar); }