mysql字符串split

SELECT 
    user_id,
    SUBSTRING_INDEX(SUBSTRING_INDEX(hobbies, ',', numbers.n), ',', -1) AS hobby
FROM 
    (SELECT 1 n UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5) numbers INNER JOIN users ON CHAR_LENGTH(hobbies) - CHAR_LENGTH(REPLACE(hobbies, ',', '')) >= numbers.n - 1;

SELECT 
    log_id,
    REGEXP_SUBSTR(message, 'user_id=(\\d+)') AS user_id
FROM 
    logs;

WITH RECURSIVE split_hobbies AS (
    SELECT 
        user_id,
        SUBSTRING_INDEX(hobbies, ',', 1) AS hobby,
        SUBSTRING_INDEX(SUBSTRING_INDEX(hobbies, ',', 2), ',', -1) AS rest
    FROM 
        users
    UNION ALL
    SELECT 
        user_id,
        SUBSTRING_INDEX(rest, ',', 1) AS hobby,
        SUBSTRING_INDEX(SUBSTRING_INDEX(rest, ',', 2), ',', -1) AS rest
    FROM 
        split_hobbies
    WHERE 
        rest IS NOT NULL
)
SELECT * FROM split_hobbies;