写了个函数，做个记录。作用是扣掉两个数组相同的部分，只保留不同的部分，也就是对称差集。

CREATE FUNCTION `array_diff`(`arr1` json, `arr2` json) RETURNS json
    NO SQL
    DETERMINISTIC
BEGIN
	RETURN (
		WITH 
		A AS (SELECT el FROM JSON_TABLE(arr1, '$[*]' COLUMNS(el INT PATH '$')) T),
		B AS (SELECT el FROM JSON_TABLE(arr2, '$[*]' COLUMNS(el INT PATH '$')) T)
		SELECT JSON_ARRAYAGG(el) FROM (
			SELECT el FROM A WHERE A.el NOT IN (SELECT el FROM B)
			UNION
			SELECT el FROM B WHERE B.el NOT IN (SELECT el FROM A)
		) AS T
	);
END

调用

select array_diff('[1,2,3]','[2,3,4]')

结果

[1, 4]