$sth = $dbh->prepare(
        sprintf "insert into %s (%s) values (%s) on duplicate key update $columns[0]=values($columns[0]),$columns[1]=values($columns[1])",
            $dbh->quote_identifier(
                $tablename

##</code><code>##


printf "insert into %s (%s) values (%s) on duplicate key update %s=values(%s),%s=values(%s)",
            $dbh->quote_identifier(
                $tablename
            ),
            join(
                ',',
                map { $dbh->quote_identifier($_) } @columns
            ),
            join( ',', ('?') x @columns ), ????