python--orm示例
建表插入数据：
import sqlalchemy
from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer,String,Date
from sqlalchemy.orm import sessionmaker
engine = create_engine("mysql+pymysql://tim:sina4433@localhost/test",
encoding = "utf-8",echo=True)
Base = declarative_base()
class User(Base):
__tablename__= "user"
id = Column(Integer,primary_key=True)
name = Column(String(32))
password = Column(String(64))
Base.metadata.create_all(engine) #创建表结构
Session_class = sessionmaker(bind=engine) #创建与数据库的会话session class,注意这里返回给session的是个类，不是实例
Session = Session_class() #生成session实例
user_obj = User(name='tim',password='sina4433') #生成你要创建的数据对象
user_obj2 = User(name = 'jack',password='abc')
print(user_obj.name,user_obj.id) #此时还没创建对象，不信打印一下id,还是None
Session.add(user_obj) # 把要创建的数据对象添加到这个session里，一会儿统一创建
Session.add(user_obj2)
print(user_obj,user_obj.id) #此时也依然还没创建
Session.commit()
查询：
import sqlalchemy
from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer,String,Date
from sqlalchemy.orm import sessionmaker
engine = create_engine("mysql+pymysql://tim:sina4433@localhost/test",
encoding = "utf-8")
Base = declarative_base()
class User(Base):
__tablename__= "user"
id = Column(Integer,primary_key=True)
name = Column(String(32))
password = Column(String(64))
def __repr__(self):
return "<%s name:%s>" % (self.id,self.name)
Base.metadata.create_all(engine) #创建表结构
Session_class = sessionmaker(bind=engine) #创建与数据库的会话session class,注意这里返回给session的是个类，不是实例
Session = Session_class() #生成session实例
# user_obj = User(name='tim',password='sina4433') #生成你要创建的数据对象
# user_obj2 = User(name = 'jack',password='abc')
# print(user_obj.name,user_obj.id) #此时还没创建对象，不信打印一下id,还是None
#
# Session.add(user_obj) # 把要创建的数据对象添加到这个session里，一会儿统一创建
# Session.add(user_obj2)
# print(user_obj,user_obj.id) #此时也依然还没创建
# Session.commit()
# data = Session.query(User).filter_by().all() #结果是一个列表
# print(data)
# data = Session.query(User).filter_by(name='tim').all() #结果是一个列表
# print(data[0].id)
# data = Session.query(User).filter_by(id=1).all()
# print(data)
# data = Session.query(User).filter(User.id>1).all()
# print(data)
# data = Session.query(User).filter(User.id>1).filter(User.id<4).all()
# print(data)
data = Session.query(User).filter(User.id>1).filter(User.id<4).first()
print(data)
# #更改数据
# data.name = "zhang"
# data.password = "Shit"
# Session.commit()
# my_user = Session.query(User).filter_by(id=1).first()
# my_user.name = 'Jack'
#
# fake_user = User(name='Rain',password='123456')
#
# Session.add(fake_user)
#
# print(Session.query(User).filter(User.name.in_(['Jack','rain'])).all())
#
# Session.rollback()
#
# print(Session.query(User).filter(User.name.in_(['Jack','rain'])).all())
多表连接：
import sqlalchemy
from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer,String,Enum,ForeignKey,DATE
from sqlalchemy.orm import sessionmaker,relationship
engine = create_engine("mysql+pymysql://tim:sina4433@localhost/test",
encoding = "utf-8")
Base = declarative_base()
class Student(Base):
__tablename__= "student"
id = Column(Integer,primary_key=True,autoincrement=True)
name = Column(String(32),nullable=True)
register_date = Column(DATE,nullable=True)
#加个关联关系
def __repr__(self):
return "<%s name:%s>"%(self.id,self.name)
class StudyRecord(Base):
__tablename__ = "StudyRecord"
id = Column(Integer,primary_key=True,autoincrement=True)
day = Column(Integer)
status = Column(String(32))
stu_id = Column(Integer,ForeignKey(Student.id))
#加个关联关系
student = relationship("Student",backref="my_study_record")
def __repr__(self):
return "<%s day:%s status:%s>"%(self.student.name,self.day,self.status)
Base.metadata.create_all(engine) #创建表结构
Session_class = sessionmaker(bind=engine) #创建与数据库的会话session class,注意这里返回给session的是个类，不是实例
session = Session_class() #生成session实例
# ret = Session.query(Student).join(Study_record).all() #这种方式需要主外键关联
# print(ret)
# ret = session.query(Student,StudyRecord).filter(Student.id==StudyRecord.stu_id).all()
# print(ret)
# s1 = Student(name="Alex",register_date='2013-02-01')
# s2 = Student(name="Jack",register_date='2014-04-01')
# s3 = Student(name="gao",register_date='2013-10-01')
# s4 = Student(name="wang",register_date='2011-11-01')
#
# study_obj1 = StudyRecord(day=1,status="YES",stu_id=1)
# study_obj2 = StudyRecord(day=2,status="NO",stu_id=1)
# study_obj3 = StudyRecord(day=3,status="YES",stu_id=1)
# study_obj4 = StudyRecord(day=1,status="YES",stu_id=2)
#
# session.add_all([s1,s2,s3,s4,study_obj1,study_obj2,study_obj3,study_obj4])
# session.commit()
#查出Alex上了几节课
stu_obj = session.query(Student).filter(Student.name=='Alex').first()
print(stu_obj.my_study_record)
多外键关联：
orm_many_fk
from sqlalchemy import Integer, ForeignKey,String,Column
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import relationship,sessionmaker
from sqlalchemy import create_engine
Base = declarative_base()
class Customer(Base):
__tablename__ = 'customer'
id = Column(Integer,primary_key=True)
name = Column(String(64))
billing_address_id = Column(Integer,ForeignKey("address.id"))
shipping_address_id = Column(Integer,ForeignKey("address.id"))
billing_address = relationship("Address",foreign_keys=[billing_address_id])
shipping_address = relationship("Address",foreign_keys=[shipping_address_id])
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
engine = create_engine("mysql+pymysql://tim:sina4433@localhost/test",
encoding = "utf-8")
Base.metadata.create_all(engine) #创建表结构
Session_class = sessionmaker(bind=engine) #创建与数据库的会话session class,注意这里返回给session的是个类，不是实例
session = Session_class() #生成session实例
orm_api:
from day11 import orm_many_fk from sqlalchemy.orm import sessionmaker Session_class = sessionmaker(bind=orm_many_fk.engine) session = Session_class() # addr1 = orm_many_fk.Address(street="Tiantongyuan",city='ChangPing',state='BJ') # addr2 = orm_many_fk.Address(street="Wudaokou",city='Haidian',state='BJ') # addr3 = orm_many_fk.Address(street="Yanjiao",city='LangFang',state='HB') # # # session.add_all([addr1,addr2,addr3]) # # c1 = orm_many_fk.Customer(name="Alex",billing_address=addr1,shipping_address=addr2) # c2 = orm_many_fk.Customer(name="Jack",billing_address=addr3,shipping_address=addr3) # # session.add_all([c1,c2]) # session.commit() obj = session.query(orm_many_fk.Customer).filter(orm_many_fk.Customer.name=="alex").first() print(obj.name,obj.billing_address,obj.shipping_address)
多对多关联：
orm_m2m:
# -*- coding: utf-8 -*-
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_engine
from sqlalchemy.orm import sessionmaker
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))
def __repr__(self):
return self.name
engine = create_engine("mysql+pymysql://root:sina4433@localhost/mytest?charset=utf8")
Base.metadata.create_all(engine) #创建表结构
Session_class = sessionmaker(bind=engine) #创建与数据库的会话session class,注意这里返回给session的是个类，不是实例
session = Session_class() #生成session实例
#插入中文，请注意在创建DATABASE时需要指定数据库字符集
b4 = Book(name='浪潮之巅',pub_date="2011-10-10")
session.add_all([b4,])
session.commit()
orm_m2m_api:
import orm_m2m from sqlalchemy.orm import sessionmaker Session_class = sessionmaker(bind=orm_m2m.engine) session = Session_class() #################################创建##################################### # b1 = orm_m2m.Book(name="learn python",pub_date="2013-12-12") # b2 = orm_m2m.Book(name="C++plus",pub_date="2012-10-22") # b3 = orm_m2m.Book(name="learn hook up girls",pub_date="2015-01-31") # a1 = orm_m2m.Author(name="Tim") # a2 = orm_m2m.Author(name="Jack") # a3 = orm_m2m.Author(name="Rain") # # b1.authors = [a1,a3] # b2.authors = [a1,a2] # b3.authors = [a1,a2,a3] # # session.add_all([b1,b2,b3,a1,a2,a3]) # session.commit() ######################################################################### ################################查询##################################### # author_obj = session.query(orm_m2m.Author).filter(orm_m2m.Author.name=='Tim').first() # print(author_obj.books) # print(author_obj.books[1].pub_date) # book_obj = session.query(orm_m2m.Book).filter(orm_m2m.Book.name=="learn python").first() # print(book_obj.authors) ######################################################################### ################################删除##################################### #通过书删除作者： # author_obj = session.query(orm_m2m.Author).filter(orm_m2m.Author.name=="tim").first() # book_obj = session.query(orm_m2m.Book).filter(orm_m2m.Book.name=="learn python").first() # book_obj.authors.remove(author_obj) #从一本书里删除一个作者 # session.commit() # # #直接删除作者 # author_obj2 = session.query(orm_m2m.Author).filter(orm_m2m.Author.name=="Jack").first() # session.delete(author_obj2) # session.commit()
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