如果数据库时间字段的类型是datetime 跟TIMESTAMP ，则mybatis中的jdbctype都是TIMESTAMP
| MySQL Type Name | Return value of GetColumnClassName | Returned as Java Class |
| DATETIME | DATETIME | java.sql.Timestamp |
| DATE | DATE | java.sql.Date |
| TIMESTAMP[(M)] | TIMESTAMP | java.sql.Timestamp |
| TIME | TIME | java.sql.Time |
