What about the inverse, going from a JSON array to rows? Perhaps I am dense on the existing MySQL JSON functionality, but I haven't been able to figure that one out.

For example, say I have a JSON array and want to insert a row for each element in the array with its value? The only way I have found is to write a bunch of JSON_EXTRACT(... '$[0]') JSON_EXTRACT(... '$[1]') etc and union them together.

Or, say I have a JSON array and want to GROUP_CONCAT() it to a single comma separated string?

In other words, I know I can do this:

SET @j = '[1, 2, 3]';

SELECT GROUP_CONCAT(JSON_EXTRACT(@j, CONCAT('$[', x.n, ']'))) AS val

  FROM

  (

    SELECT 0 AS n

    UNION

    SELECT 1 AS n

    UNION

    SELECT 2 AS n

    UNION

    SELECT 3 AS n

    UNION

    SELECT 4 AS n

    UNION

    SELECT 5 AS n

  ) x

But that hurts my eyes. And my heart.

How can I do something like:

SET @j = '[1, 2, 3]';

SELECT GROUP_CONCAT(JSON_EXTRACT(@j, '$[ * ]'))

... and have it concatenate together the values in the array vs. the JSON array itself.

I guess what I'm looking for here is some sort of JSON_SPLIT along the lines of:

SET @j = '[1, 2, 3]';

SELECT GROUP_CONCAT(val) FROM JSON_SPLIT(JSON_EXTRACT(@j, '$[ * ]'), '$')

Which, speaking of, a STRING_SPLIT(val, 'separator') table returning function is also sorely needed.