from sqlalchemy import *
from sqlalchemy.orm import declarative_base,sessionmaker

db_url = "mysql+pymysql://root:123456@127.0.0.1:3306/student?charset=utf8mb4"  #创建连接对象
engine = create_engine(db_url)  #与数据库进行连接

Base = declarative_base()     # 执行函数，返回一个基类


Session = sessionmaker(bind=engine
                       ,autoflush=False
                       ,autocommit = False
                       )

def get_db():
    db = Session()
    try:
        yield db
    finally:
        db.close()