Oracle 18c

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CREATE TABLE table_name ( code ) AS
SELECT '[1],[22],[333],[4444],[55555],[666666],[7777777],[88888888],[999999999],[0000000000]' FROM DUAL
1 rows affected

SELECT DISTINCT REPLACE(SUBSTR (REGEXP_SUBSTR (code,'[^,]+',1,LEVEL),2,8),']','') code
FROM table_name
CONNECT BY REGEXP_SUBSTR (code, '[^,]+', 1, LEVEL) IS NOT NULL;


CODE


99999999

4444

55555

1

333

22

666666

88888888

00000000

7777777


WITH rsqfc ( code, start_pos, end_pos ) AS (
  SELECT code,
         1,
         INSTR( code, ',', 1 )
  FROM   table_name
UNION ALL
  SELECT code,
         end_pos + 1,
         INSTR( code, ',', end_pos + 1 )
  FROM   rsqfc
  WHERE  end_pos > 0
)
SELECT DISTINCT
       REPLACE(
         CASE end_pos
         WHEN 0
         THEN SUBSTR( code, start_pos + 1, 8 )
         ELSE SUBSTR( code, start_pos + 1, LEAST( end_pos - start_pos - 1, 8 ) )
         END,
         ']'
       ) AS code
FROM   rsqfc;


CODE


99999999

4444

55555

1

333

22

666666

88888888

00000000

7777777