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:[email protected]/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:[email protected]/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:[email protected]/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)