php natural order sorting of mysql select rows

Question

I'm running a select that returns alphanumeric results, e.g:

ABC-1
ABC-2
ABC-10
SAM-1
SAM-2
SAM-10
SAM-20

I've tried using:

ORDER BY CAST(mid(field_name, 6, LENGTH(class) -5) AS unsigned)

and

ORDER BY filed_name + 0 ASC

this has helped put some order but I cant seem to order -2 before -10

many thanks

Answer 1

How about

ORDER BY 
  LEFT(field_name, INSTR(field_name, '-') - 1),
  CAST(
    SUBSTRING(field_name, INSTR(field_name, '-') + 1) AS INTEGER
  )