更新所有模块框架，建表已写好，学生查询模块已经写好，正在写新增模块。

students/databases.py

@@ -0,0 +1,25 @@
+# databases链接数据库
+
+from sqlalchemy import *
+from sqlalchemy.orm import sessionmaker,declarative_base
+
+db_url = "mysql+pymysql://root:420821@localhost:3306/student_manage_system?charset=utf8mb4"
+
+engine1 = create_engine(db_url)
+
+Base = declarative_base()
+
+Session = sessionmaker(bind=engine1
+                               ,autoflush=False
+                               ,autocommit=False)
+
+def get_db():
+    db = Session()
+    try:
+        yield db
+    finally:
+        db.close()
+
+
+
+