Base 36 to Base 10 conversion using SQL only

Question

A situation has arisen where I need to perform a base 36 to base 10 conversion, in the context of a SQL statement. There doesn\'t appear to be anything built into Oracle 9

Answer 1

For T-SQL the following logic will perform the task that the Oracle code above does. This is generic general solution and will support Base-X to Base-10:

select
    sum(power(base,pos-1) *
            case when substring(cnv,pos,1) between '0' and '9' then 
                cast(substring(cnv,pos,1) as int) 
            else 10 + ascii(upper(substring(cnv,pos,1))) - ascii('A') end)
    from (values(reverse('01Z'), 36)) as t(cnv,base)
        left join (values(1),(2),(3),(4),(5),(6)) as x(pos)
            on pos <= len(cnv)

To use with other bases just use:

from (select cnv = reverse('FF'), base=16) as t

or

from (select cnv = reverse('101'), base=2) as t

Note that to support strings longer than 6 you would need to add more values to the position vector.

Answer 2

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)
         )
)