Python sqlalchemy的基本使用

示例代码

from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Integer, Column, String, DATE, Table, BigInteger

#生成引擎
engine = create_engine("mysql+pymysql://root:123456@localhost/mytest?charset=utf8")
#常见ORM基类
Base = declarative_base()

#创建学生表
class Student(Base):
    __tablename__ = 'student'
    id = Column(Integer, primary_key=True)
    name = Column(String(32))
    password = Column(String(64))
    mobile = Column(BigInteger)
    gradesclasses = Column(String(64))

#创建老师表
class Teacher(Base):
    __tablename__ = 'teacher'
    id = Column(Integer, primary_key=True)
    name = Column(String(32))
    password = Column(String(64))
    mobile = Column(BigInteger)

if __name__ == "__main__":
    Base.metadata.create_all(engine)

ORM多外键关联

#ORM多外键关联

from sqlalchemy import create_engine
from sqlalchemy import Integer, ForeignKey, String, Column
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import relationship

engine = create_engine("mysql+pymysql://skymyyang:666666@mfgskymyyang.chinacloudapp.cn/myyang",
                       encoding='utf-8')
Base = declarative_base()

class Customer(Base):
    __tablename__ = 'customer'
    id = Column(Integer, primary_key=True)
    name = Column(String(32))

    billing_address_id = Column(Integer, ForeignKey("address.id"))  #账单地址
    shipping_address_id = Column(Integer, ForeignKey("address.id")) #邮寄地址 这两个地址同时关联了 同一个地址表

    billing_address = relationship("Address", foreign_keys = [billing_address_id])
    shipping_address = relationship("Address", foreign_keys = [shipping_address_id])  #通过关联差address表

class Address(Base):
    __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.street

Base.metadata.create_all(engine) #创建表结构

然后进行查询以及数据插入

from daynine import orm_mang_fk

from sqlalchemy.orm import session,sessionmaker

Session_class = sessionmaker(bind=orm_mang_fk.engine)
session = Session_class()#生成session实例 相当于cursor

# addr1 = orm_mang_fk.Address(street="Tiantongyuan", city="Changping", state="BJ")
# addr2 = orm_mang_fk.Address(street="Wudaokou", city="Haidian", state="BJ")
# addr3 = orm_mang_fk.Address(street="Yanjiao", city="LangFang", state="HB")
# session.add_all([addr1, addr2, addr3])
# c1 = orm_mang_fk.Customer(name = "skymyyang", billing_address_id = 4, shipping_address_id = 5)
# c2 = orm_mang_fk.Customer(name = "mayun",  billing_address_id = 6, shipping_address_id = 6)
# session.add_all([c1, c2])
# session.commit()
obj = session.query(orm_mang_fk.Customer).filter(orm_mang_fk.Customer.name =="skymyyang").first()
print(obj.name, obj.billing_address, obj.shipping_address)

ORM多对多

#ORM多对多

from sqlalchemy import create_engine
from sqlalchemy import Integer, ForeignKey, String, Column, DATE, Table
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import relationship
#创建引擎
engine = create_engine("mysql+pymysql://skymyyang:666666@mfgskymyyang.chinacloudapp.cn/myyang?charset=utf8",encoding='utf-8')
#生成ORM基类
Base = declarative_base()
book_m2m_author = Table('book_m2m_author', Base.metadata,
                        Column('book_id', Integer, ForeignKey('books.id')),
                        Column('author_id', Integer, ForeignKey('authors.id')),
)

class Book(Base):
    __tablename__ = 'books'
    id = Column(Integer, primary_key=True)
    name = Column(String(64))
    pub_date = Column(DATE)
    authors = relationship('Author', secondary=book_m2m_author, backref = 'books')

    def __repr__(self):
        return self.name

class Author(Base):
    __tablename__ = 'authors'
    id = Column(Integer, primary_key=True)
    name = Column(String(32))
    email = Column(String(64))

    def __repr__(self):
        return self.name

if __name__  ==  '__main__':
    Base.metadata.create_all(engine)