Oracle sort, Oracle

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--Oracle 11g Express Edition
--please drop objects you've created at the end of the script 
--or check for their existance before creating
--'\\' is a delimiter

select *
from (select '4.6' as col from dual union all
      select '5.2' as col from dual union all
      select '3.1' as col from dual union all
      select '5.3' as col from dual union all
      select '3.5' as col from dual union all
      select '5.4' as col from dual union all
      select '2.11' as col from dual union all
      select '2.12' as col from dual union all
      select '2.13' as col from dual union all
      select '2.14' as col from dual union all
      select '2.15' as col from dual union all
      select '5.5' as col from dual union all
      select '5.6' as col from dual union all
      select '5.7' as col from dual union all
      select '2.17' as col from dual union all
      select '5.8' as col from dual union all
      select '5.9' as col from dual
     ) x
order by cast(regexp_substr(col, '[^.]+', 1, 1) as number),
         cast(regexp_substr(col, '[^.]+', 1, 2) as number),
         cast(regexp_substr(col, '[^.]+', 1, 3) as number),
         cast(regexp_substr(col, '[^.]+', 1, 4) as number)


absolute service time: 0,84 sec