mysql 中数组类型转换

SELECT id, SUBSTRING_INDEX(SUBSTRING_INDEX(array_str, ',', numbers.n), ',', -1) AS val
FROM example
JOIN (
    SELECT 1 n UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5
) numbers
WHERE numbers.n <= LENGTH(array_str) - LENGTH(REPLACE(array_str, ',', '')) + 1;

SELECT id, JSON_UNQUOTE(JSON_EXTRACT(array_json, CONCAT('$[', index, ']'))) AS val
FROM example
JOIN (
    SELECT 0 index UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4
) indexes
WHERE JSON_LENGTH(array_json) > indexes.index;

SELECT e.id, GROUP_CONCAT(ae.value SEPARATOR ',') AS array_str
FROM example e
JOIN array_elements ae ON e.array_id = ae.id
GROUP BY e.id;