如何在oracle中拆分单词

SELECT REGEXP_SUBSTR('Hello world, how are you?', '[[:alnum:]]+', 1, LEVEL) AS word
FROM dual
CONNECT BY REGEXP_SUBSTR('Hello world, how are you?', '[[:alnum:]]+', 1, LEVEL) IS NOT NULL;

CREATE TABLE words (
  word VARCHAR2(100)
);

INSERT INTO words (word)
SELECT REGEXP_SUBSTR('Hello world, how are you?', '[[:alnum:]]+', 1, LEVEL) AS word
FROM dual
CONNECT BY REGEXP_SUBSTR('Hello world, how are you?', '[[:alnum:]]+', 1, LEVEL) IS NOT NULL;

SELECT word, COUNT(*) AS count
FROM (
  SELECT REGEXP_SUBSTR('Hello world, how are you?', '[[:alnum:]]+', 1, LEVEL) AS word
  FROM dual
  CONNECT BY REGEXP_SUBSTR('Hello world, how are you?', '[[:alnum:]]+', 1, LEVEL) IS NOT NULL
)
GROUP BY word;