Conversion de base 36 à base 10 en utilisant SQL uniquement

select sum(position_value) from
(
  select power(36,position-1) * case when digit between '0' and '9' 
                                     then to_number(digit)
                                     else 10 + ascii(digit) - ascii('A')
                                end
          as position_value
    from (
          select substr(input_string,length(input_string)+1-level,1) digit, 
                 level position
            from (select '01Z' input_string from dual)
            connect by level <= length(input_string)
         )
)