+---------------------------------------+\nmysql> SELECT JSON_KEYS(\'{"a": 1, "b": {"c": 30}}\', \'$.b\');\n+----------------------------------------------+\n| JSON_KEYS(\'{"a": 1, "b": {"c": 30}}\', \'$.b\') |\n+----------------------------------------------+\n| ["c"]                                        |\n+----------------------------------------------+\n','https://dev.mysql.com/doc/refman/8.0/en/json-search-functions.html');