MariaDB 10.0.X中，动态列（Dynamic Columns），可以支持 JSON 格式来获取数据。 为了兼容传统SQL语法，MariaDB 10和MySQL5.7支持
mysql> UPDATE assets SET dynamic_cols=COLUMN_ADD(dynamic_cols, 'warranty', '3 years')
-> WHERE item_name='Thinkpad Laptop';
Query OK, 1 row affected (0.01 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> 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"} |
+-----------------+----------------------------------------+
2 rows in set (0.00 sec)
