my @updates = map {$dbh->quote_identifier($_) . ' = (?)'} ('call 1 comment', 'call 2 comment', 'call 3 comment', 'call 4 comment');
my $name_field = $dbh->quote_identifier('last name');
my $update_string = join ", ", @updates;

my $sql = qq{UPDATE $table SET $update_string WHERE $name_field = (?)};
print "$sql\n";

my $sth = $dbh->prepare_cached($sql);
$sth->execute('foo','bar','baz','qux','smith');