新增databases.py把所有建表基类统一成一个，才可以链接外键。

Teachers/model/tea_model.py

@@ -1,3 +1,4 @@
+from databases import engine_all,Base_all,Session
 from Teachers.database import *
 from datetime import datetime
 from sqlalchemy import *
@@ -7,7 +8,7 @@ class Gender(str,enum.Enum):
     m = '男'
     f = '女'
 
-class Tea(Base):
+class Tea(Base_all):
     __tablename__ = 'teachers'
     id = Column(Integer
                     , primary_key=True