from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, DATE, ForeignKey
from sqlalchemy.orm import relationship, sessionmakerconnect = create_engine("mysql+pymysql://root:123456@localhost:3306/test",encoding="utf-8",echo=False)  # 连接数据库，echo=True =>把所有的信息都打印出来Base = declarative_base()  # 生成ORM基类class Student(Base):  # 学生表__tablename__ = "student"id = Column(Integer, primary_key=True)name = Column(String(32), nullable=False)register_date = Column(DATE, nullable=False)def __repr__(self):return "<{0} name:{1}>".format(self.id, self.name)class StudentRecord(Base):   # 学生学习记录表__tablename__ = "study_record"id = Column(Integer, primary_key=True)day = Column(Integer, nullable=False)status = Column(String(32), nullable=False)stu_id = Column(Integer, ForeignKey("student.id"))  # 关联外键#关联student表，然后我需要在study_record里通过student这个字段，就可以去查Student类里面所有的字段，# 反过来利用backref="my_study_record"中的my_study_record，在student表里通过my_study_record这个字段反查study_record类里面的所有字段，Student = relationship("Student", backref="my_study_record")def __repr__(self):return "<name:{0} day:{1} stu_id:{2}>".format(self.Student.name, self.day, self.stu_id)Base.metadata.create_all(connect)  # 创建学生表和学生记录表，在第一次创建后注释session_class = sessionmaker(connect)  # 创建与数据库的会话session class ,这里返回给session的是个class,不是实例
session = session_class()  # 生成session实例#在两个表中插入数据
stu1 = Student(name="test", register_date="2017-05-30")
stu2 = Student(name="test2", register_date="2017-06-30")
record1 = StudentRecord(day=1, status="Y", stu_id=1)
record2 = StudentRecord(day=2, status="Y", stu_id=1)
session.add_all([record1, record2])
session.commit()

stu_obj = session.query(Student).filter_by(name="test").first()
print(stu_obj.my_study_record)  # 在学生表里查学生对应的学习记录record_obj = session.query(StudentRecord).first()
print(record_obj.Student.name)  # 在学生记录表里面查学习记录对应学生的名字#输出
[<name:test day:1 stu_id:1>, <name:test day:2 stu_id:1>]test

from sqlalchemy import Integer, ForeignKey, String, Column
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import relationship
from sqlalchemy import create_engineBase = declarative_base()  # orm基类class Customer(Base):   # 消费者表__tablename__ = "customer"id = Column(Integer, primary_key=True)name = Column(String(64))#创建两个外键，都指向address.idbilling_address_id = Column(Integer, ForeignKey("address.id"))shipping_address_id = Column(Integer, ForeignKey("address.id"))#因为有两个外键，需要通过foreign_keys=[外键字段]告诉sqlalchemy关联哪个外键了，不然就会报错billing_address = relationship("Address", foreign_keys=[billing_address_id])shipping_address = relationship("Address", foreign_keys=[shipping_address_id])class Address(Base):   # 收货地址表__tablename__ = "address"id = Column(Integer, primary_key=True)street = Column(String(64))city = Column(String(64))state = Column(String(64))def __repr__(self):return self.state + "-" + self.city + "-" + self.streetconnect = create_engine("mysql+pymysql://root:123456@localhost:3306/test",encoding="utf-8",echo=False)  # 连接数据库，echo=True =>把所有的信息都打印出来Base.metadata.create_all(connect)  # 创建所有的表

import many_foreign_key # 导出表结构创建模块
from sqlalchemy.orm import sessionmaker#创建session与数据库会话类，生成session实例
session_class = sessionmaker(bind=many_foreign_key.connect)
session = session_class()
#创建address
address1 = many_foreign_key.Address(street="nanshanqu", city="shenzhen", state="guangdong")
address2 = many_foreign_key.Address(street="baoanqu", city="shenzhen", state="guangdong")
#创建consumers
c1 = many_foreign_key.Customer(name="test", billing_address=address1, shipping_address=address1)
c2 = many_foreign_key.Customer(name="test1", billing_address=address2, shipping_address=address1)
#添加session提交
session.add_all([address1, address2, c1, c2])
session.commit()

import many_foreign_key
from sqlalchemy.orm import sessionmakerobj = session.query(many_foreign_key.Customer).filter_by(name="test1").first()
print(obj.name, obj.billing_address, obj.shipping_address)#输出
test1 guangdong-shenzhen-baoanqu guangdong-shenzhen-nanshanqu

from sqlalchemy import Table, Column, Integer, String, DATE, ForeignKey
from sqlalchemy.orm import relationship
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import create_engineBase = declarative_base()  # 创建orm基类# 创建一张中间表，用于对book表和author表之前的多对多关联， 中间表建立后由ORM自动维护
book_m2m_author = Table("book_m2m_author", Base.metadata,Column("id", Integer, primary_key=True),Column('books_id', Integer, ForeignKey("books.id")),Column('authors_id', Integer, ForeignKey("authors.id")))class Book(Base):__tablename__ = "books"id = Column(Integer, primary_key=True)name = Column(String(64))pub_date = Column(DATE)#关联authors表和中间表book_m2m_author，即可通过books反查出Author表中的数据或者#通过authors反查出books表中的数据authors = relationship("Author", secondary=book_m2m_author, backref="books")def __repr__(self):return self.nameclass Author(Base):__tablename__ = "authors"id = Column(Integer,primary_key=True)name = Column(String(32))def __repr__(self):return self.nameconnect = create_engine("mysql+pymysql://root:123456@localhost:3306/test?charset=utf8",echo=False)  # 连接数据库，echo=True =>把所有的信息都打印出来Base.metadata.create_all(connect)  # 创建所有表

import m2m_foreign_key
from sqlalchemy.orm import sessionmaker#创建session与数据库会话类，生成session实例
session_class = sessionmaker(bind=m2m_foreign_key.connect)
session = session_class()
#创建book信息
b1 = m2m_foreign_key.Book(name="Python", pub_date="2017-08-08")
b2 = m2m_foreign_key.Book(name="JAVA", pub_date="2017-10-08")
b3 = m2m_foreign_key.Book(name="C", pub_date="2017-11-08")
#创建author信息
a1 = m2m_foreign_key.Author(name="test")
a2 = m2m_foreign_key.Author(name="test1")
a3 = m2m_foreign_key.Author(name="test2")
#创建中间表信息
b1.authors = [a1, a3]
b2.authors = [a1, a2, a3]session.add_all([b1, b2, b3, a1, a2, a3])session.commit()

import m2m_foreign_key
from sqlalchemy.orm import sessionmaker#创建session与数据库会话类，生成session实例
session_class = sessionmaker(bind=m2m_foreign_key.connect)
session = session_class()authors_obj = session.query(m2m_foreign_key.Author).filter_by(name="test").first()
print(authors_obj.books)  # 通过books反查出books表中的数据
book_obj = session.query(m2m_foreign_key.Book).filter(m2m_foreign_key.Book.id == 2).first()
print(book_obj.authors)  # 通过authors反查出authors表中的数据
#输出
[Python, JAVA]
[test, test1, test2]

import m2m_foreign_key
from sqlalchemy.orm import sessionmaker#创建session与数据库会话类，生成session实例
session_class = sessionmaker(bind=m2m_foreign_key.connect)
session = session_class()#通过书删除作者
author_obj = session.query(m2m_foreign_key.Author).filter_by(name="test1").first()
book_obj = session.query(m2m_foreign_key.Book).filter_by(name="JAVA").first()
book_obj.authors.remove(author_obj)  # 从一本书里删除一个作者
session.commit()#删除作者，会把这个作者跟所有书的关联关系数据也自动删除
author_obj =session.query(m2m_foreign_key.Author).filter_by(name="test").first()
# print(author_obj.name , author_obj.books)
s.delete(author_obj)
s.commit()