Error in MySQL documentation JSON_VALUE

[Derek Wolfe]

The documentation is incorrect in that is states the following 2 statements are equivalent.

SELECT JSON_VALUE(json_doc, path RETURNING type);
SELECT CAST(JSON_UNQUOTE(JSON_EXTRACT(json_doc, path)) AS type);

This is incorrect due to how JSON_EXTRACT and JSON_VALUE treat null values differently. This can be easily shown:

SET @object = JSON_OBJECT('index', null);

SELECT JSON_VALUE(@object, '$.index' RETURNING char);
SELECT CAST(JSON_UNQUOTE(JSON_EXTRACT(@object, '$.index')) AS char);