MySQL:
JSON_ARRAYAGG
Syntax:
JSON_ARRAYAGG(col_or_expr) [over_clause]
Aggregates a result set as a single JSON array whose elements consist
of the rows. The order of elements in this array is undefined. The
function acts on a column or an expression that evaluates to a single
value. Returns NULL if the result contains no rows, or in the event of
an error.
As of MySQL 8.0.14, this function executes as a window function if
over_clause is present. over_clause is as described in
https://dev.mysql.com/doc/refman/8.0/en/window-functions-usage.html.
URL: https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html
Example
mysql> SELECT o_id, attribute, value FROM t3;
+------+-----------+-------+
| o_id | attribute | value |
+------+-----------+-------+
| 2 | color | red |
| 2 | fabric | silk |
| 3 | color | green |
| 3 | shape | square|
+------+-----------+-------+
4 rows in set (0.00 sec)
mysql> SELECT o_id, JSON_ARRAYAGG(attribute) AS attributes
> FROM t3 GROUP BY o_id;
+------+---------------------+
| o_id | attributes |
+------+---------------------+
| 2 | ["color", "fabric"] |
| 3 | ["color", "shape"] |
+------+---------------------+
2 rows in set (0.00 sec)