新增databases.py把所有建表基类统一成一个，才可以链接外键。

students/main.py

@@ -5,17 +5,23 @@ from students.model import students_model
 from contextlib import asynccontextmanager
 
 # 合并接口
-Students_API = APIRouter()
-Students_API.include_router(s_api)
-
-# 自测接口
 @asynccontextmanager
-async def lifespan(app: FastAPI):
+async def S_Router(Students_API: APIRouter):
     Base.metadata.create_all(engine1)
     yield
     engine1.dispose()
 
-app = FastAPI(title="学生管理系统",lifespan=lifespan) # 这里必须把上面写的加上
+Students_API = APIRouter(lifespan=S_Router)
+Students_API.include_router(s_api)
+
+# 自测接口
+@asynccontextmanager
+async def S_Fastapi(app: FastAPI):
+    Base.metadata.create_all(engine1)
+    yield
+    engine1.dispose()
+
+app = FastAPI(title="学生管理系统",lifespan=S_Fastapi) # 这里必须把上面写的加上
 app.include_router(s_api,tags=["students"])