Sorting N non-unique digits (with repetitions) in Oracle SQL using RPAD, TRANSLATE, REGEXP_REPLACE, XMLQuery

all-variants.sql

with v(a) as (select to_char(n,'fm0000') from xmltable('9741,2415,9100,5532' columns n int path'.'))
select
  a
 ,translate(
     regexp_replace(
       '0a0b0c0d1a1b1c1d2a2b2c2d3a3b3c3d4a4b4c4d5a5b5c5d6a6b6c6d7a7b7c7d8a8b8c8d9a9b9c9d'
      ,'('
       ||substr(a,1,1)||'a|'
       ||substr(a,2,1)||'b|'
       ||substr(a,3,1)||'c|'
       ||substr(a,4,1)||'d'
       ||')|\d[abcd]'
      ,'\1'
     )
   ,'xabcd','x'
 ) 
  as sorted_1
 ,
    rpad('0',4-length(replace(a,'0')),'0')
  ||rpad('1',4-length(replace(a,'1')),'1')
  ||rpad('2',4-length(replace(a,'2')),'2')
  ||rpad('3',4-length(replace(a,'3')),'3')
  ||rpad('4',4-length(replace(a,'4')),'4')
  ||rpad('5',4-length(replace(a,'5')),'5')
  ||rpad('6',4-length(replace(a,'6')),'6')
  ||rpad('7',4-length(replace(a,'7')),'7')
  ||rpad('8',4-length(replace(a,'8')),'8')
  ||rpad('9',4-length(replace(a,'9')),'9')
  as sorted_2
 ,
   translate(
       translate(
           '0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVW'
          ,'#'||translate(
                   '0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVW'
                  ,'#'
                    ||chr(48+0+(ascii(substr(a,1,1))-48)*4)
                    ||chr(48+1+(ascii(substr(a,2,1))-48)*4)
                    ||chr(48+2+(ascii(substr(a,3,1))-48)*4)
                    ||chr(48+3+(ascii(substr(a,4,1))-48)*4)
                  ,'#'
                )
         ,'#'
        )
      ,'0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVW'
      ,'0000111122223333444455556666777788889999'
   ) 
   as sorted_3
 ,xmlquery('string-join(for $cp in string-to-codepoints(.) order by $cp return codepoints-to-string(($cp)), "")'
   passing a returning content).getstringval() 
   as sorted_4
from v