I need to index a field that contains values like:

RTA-1
RTA-2
RTA-3
RTA-3a
RTA-10
RTA-10a
RTA-10b

etc. How would you construct an index statement that would sort in the order shown?

index on left(sponsor_id,4) + str(val(substr(sponsor_id,5,8))) to temp

almost works but misses the alpha in the last position.


Thanks