Syntax
------

COLUMN_JSON(dyncol_blob)

Description
-----------

Returns a JSON representation of data in dyncol_blob. Can also be used to
display nested columns. See dynamic columns for more information.

Example
-------

select item_name, COLUMN_JSON(dynamic_cols) from assets;
+-----------------+----------------------------------------+
| item_name       | COLUMN_JSON(dynamic_cols)              |
+-----------------+----------------------------------------+
| MariaDB T-shirt | {"size":"XL","color":"blue"}           |
| Thinkpad Laptop | {"color":"black","warranty":"3 years"} |
+-----------------+----------------------------------------+

Limitation: COLUMN_JSON will decode nested dynamic columns at a nesting level
of not more than 10 levels deep. Dynamic columns that are nested deeper than
10 levels will be shown as BINARY string, without encoding.

URL: https://mariadb.com/kb/en/column_json/