获取Oracle中以逗号分隔的列中可用数据的唯一长度

WITH recursive_cte (str, remaining_str) AS (
  SELECT 
    SUBSTR(column_name, 1, INSTR(column_name, ',') - 1) AS str,
    SUBSTR(column_name, INSTR(column_name, ',') + 1) AS remaining_str
  FROM 
    table_name
  WHERE 
    column_name LIKE '%,%'
  UNION ALL
  SELECT 
    SUBSTR(remaining_str, 1, INSTR(remaining_str, ',') - 1) AS str,
    SUBSTR(remaining_str, INSTR(remaining_str, ',') + 1) AS remaining_str
  FROM 
    recursive_cte
  WHERE 
    remaining_str LIKE '%,%'
)
SELECT 
  str
FROM 
  recursive_cte
UNION ALL
SELECT 
  remaining_str
FROM 
  recursive_cte
WHERE 
  remaining_str NOT LIKE '%,%';

WITH recursive_cte (str, remaining_str) AS (
  -- 上述查询的代码
)
SELECT 
  LENGTH(str) AS unique_length
FROM 
  (
  SELECT 
    DISTINCT str
  FROM 
    recursive_cte
  UNION ALL
  SELECT 
    DISTINCT remaining_str
  FROM 
    recursive_cte
  WHERE 
    remaining_str NOT LIKE '%,%'
  )
ORDER BY 
  unique_length;