1146表不’；在flaskpython中不存在，因为它映射了错误的数据库

我尝试将flask与两个数据库（MySQL）连接，一个是部门，另一个是分配 当我尝试联接表时，会显示表Department.assigned不存在的错误。但是assigned映射到Assign数据库。 我尝试了以下代码：

app.config['SQLALCHEMY_DATABASE_URI']='mysql://root:pwd@localhost:3306/Department'

app.config['SQLALCHEMY_BINDS']= {
    'my_sql1': 'mysql://root:pwd@localhost:3306/Assign'}

app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False

db=SQLAlchemy(app)
class Course(db.Model):
    __tablename__ = 'courses'
    __table_args__ = {'extend_existing': True}
    ID = db.Column(db.String(5000),primary_key=True)
    Name = db.Column(db.String(5000))
    cap = db.Column(db.String(5000))


class assigned(db.Model):
    __bind_key__ = 'my_sql1'
    __tablename__ = 'assigned' 
    __table_args__ = {'extend_existing': True}
    empID = db.Column(db.Integer,primary_key=True)
    projID = db.Column(db.Integer)
    role = db.Column(db.String(5000))

chart1 = aliased(Course)
chart2 = aliased(assigned)

a=db.session.query(chart1.ID,chart1.cap).join(chart2,(chart1.ID == chart2.role)).filter(chart1.cap ==82).all()
`````