多对多表间关系

创建表结构：

from sqlalchemy.ext.declarative import declarative_base

Base = declarative_base()

from sqlalchemy import Column, Integer, String, ForeignKey
from sqlalchemy.orm import relationship


class Girls(Base):
    __tablename__ = "girl"
    id = Column(Integer, primary_key=True)
    name = Column(String(32))

    #创建关系
    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
engine = create_engine("mysql+pymysql://root:@127.0.0.1:3306/day127?charset=utf8")

Base.metadata.create_all(engine)

 secondary：指定关系表