class Marine_hydrology(db.Model): tablename = 'marine_hydrology' id = db.Column(db.Integer, primary_key=True, autoincrement=True) route = db.Column(db.String(100), nullable=False) data_set_name = db.Column(db.String(100), nullable=False) data_set_size = db.Column(db.String(100), nullable=False) data_set_source = db.Column(db.String(1000), nullable=False) data_set_time_frame = db.Column(db.String(100), nullable=False) data_set_loc = db.Column(db.String(100), nullable=False) data_set_abstract = db.Column(db.String(10000), nullable=False) class Hydrology_data(db.Model): tablename = 'hydrology_data' id = db.Column(db.Integer, primary_key=True, autoincrement=True)data_route = db.Column(db.String(100), nullable=False) data_name = db.Column(db.String(100), nullable=False) data_time = db.Column(db.DateTime, nullable=False, default=datetime.now) data_format = db.Column(db.String(100), nullable=False) data_kind = db.Column(db.String(100), nullable=False) data_refresh = db.Column(db.String(100), nullable=False) uid_hydrology = db.Column(db.Integer, db.ForeignKey("marine_hydrology.id")) down_time = db.Column(db.Integer, nullable=False)类图怎么画?两个类的关系怎么画?
时间: 2024-03-06 19:50:13 浏览: 7
下面是这两个类的UML类图:
```
+-------------------+ +---------------------+
| Marine_hydrology| | Hydrology_data |
+-------------------+ +---------------------+
| -id: int | | -id: int |
| -route: str | | -data_route: str |
| -data_set_name: str| | -data_name: str |
| -data_set_size: str| | -data_time: datetime |
| -data_set_source: str| | -data_format: str |
| -data_set_time_frame: str| | -data_kind: str |
| -data_set_loc: str| | -data_refresh: str |
| -data_set_abstract: str| | -uid_hydrology: int |
+-------------------+ | -down_time: int |
+---------------------+
```
这两个类之间的关系是:`Marine_hydrology`类和`Hydrology_data`类之间是一对多的关系,即`Marine_hydrology`类可以有多个`Hydrology_data`类的实例,而每个`Hydrology_data`类的实例都属于一个`Marine_hydrology`类的实例。因此,`Hydrology_data`类中有一个外键`uid_hydrology`,它指向`Marine_hydrology`类的实例的`id`属性。在UML类图中,可以使用带箭头的实线来表示这种关系,箭头指向`Marine_hydrology`类。