昨天更新了博客不知對各位職場的大佬有沒有幫助，如果沒有看到的請用小手狠狠地戳這裏

Flask中的的SQLAlchemy

今天呢，我們來說一下多對多表的關系，知道不？開始之前我先說一個事，昨晚更新了博客之後我夢到一位女粉絲走到我面請輕輕的吻了我，嘖嘖嘖，味可好了~~~~

1.多對多表關系

from sqlalchemy import Column,Integer,String,ForeignKey
from sqlalchemy.orm import relationship
from sqlalchemy.ext.declarative import declarative_base
Base 
 
= declarative_base()

class Girls(Base):
    __tablename__ = ‘girl‘
    id = Column(Integer,primary_key=True)
    name = Column(String(32))
    #表的關系
    girl2boy = relationship("Boys",secondary = "hotel",backref = "boy2girl")

class Boys(Base):
    __tablename__ = ‘boy‘
    id = Column(Integer,primary_key=True
 
)
    name = Column(String(32))


class Hotel(Base):
    __tablename__=‘hotel‘
    id = Column(Integer,primary_key=True)
    girl_id = Column(Integer,ForeignKey("girl.id"))
    boy_id = Column(Integer,ForeignKey("boy.id"))

from sqlalchemy import create_engine
#這裏不懂得，戳紫色的字！！
engine = create_engine("
 
mysql+pymysql://root:[email protected]:3306/day127?charset=utf8")

Base.metadata.create_all(engine)

2.簡單的操作

#curd_M2M.py

from sqlalchemy.orm import sessionmaker
from SQL.curd_M2m import engine
from SQL.curd_M2m import Boys,Girls,Hotel
Session = sessionmaker(engine)
db_session = Session()

#t通過想Boy添加數據添加girl和hotel數據。relationship反向
boy = Boys(name="李誌強")
boy.boy2girl = [Girls(name="哇哈哈"),Girls(name="喜洋洋")]
db_session.add(boy)
db_session.commit()
db_session.close()


#t通過想Girl添加數據添加boy和hotel數據。relationship正向
girl_obj = Girls(name="李二短",girl2boy=[Boys(name="任二狗"),Boys(name="任夢")])
db_session.add(girl_obj)
db_session.commit()
db_session.close()



# 查詢 正向查詢
ret = db_session.query(Girls).all()
for girl in ret:
    for boy in girl.girl2boy:
#這裏說一下，註意表的結構，有很多的小的細節不註意就會報錯，查到girl信息，再次遍歷的時候註意girl.girl2boy，正向查詢
        print(girl.name , boy.name)

# 查詢 反向查詢
ret = db_session.query(Boys).all()
for boy in  ret:
    for girl in boy.boy2girl:
        print(boy.name,girl.name)

Flask中的的SQLAlchemy2