SQLAlchemy对数据库的增删改查操作

创建指定的数据库表：

from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column,Integer,String,create_engine #创建一个orm模型基类
Base=declarative_base() class User(Base): __tablename__="user" id=Column(Integer,primary_key=True,autoincrement=True) name=Column(String(32),index=True) #创建数据库连接
engine=create_engine("mysql+pymysql://root:1234@127.0.0.1:3306/lgweb?charset=utf8") #调用engine 创建所有继承base类的数据表类
Base.metadata.create_all(engine)

对数据库中表数据的添加及批量添加操作：

from creat_table import engine,User from sqlalchemy.orm.session import sessionmaker #创建指定数据库会话
Session=sessionmaker(engine) #打开会话窗口
db_session=Session() # user_obj=User(name="tom") # user1=User(name="lisa")

#相当于insert into # db_session.add(user_obj) # db_session.add(user1)
db_session.add_all([ User(name="婉君"),User(name="小芬"),User(name="程洁"),User(name="思宇") ]) #提交数据
db_session.commit() db_session.close()

 单表查询：

from creat_table import engine,User from sqlalchemy.orm.session import sessionmaker Session=sessionmaker(engine) db_session=Session() # user_list=db_session.query(User).filter(User.id>=4).all()
user_list=db_session.query(User).filter_by(id>=4).all() for user in user_list: print(user.id,user.name)

 更新数据：

from creat_table import engine,User from sqlalchemy.orm.session import sessionmaker Session=sessionmaker(engine) db_session=Session() db_session.query(User).filter_by(name="小芬").update({"name":"晓晓"}) db_session.commit()

删除数据：

from creat_table import engine,User from sqlalchemy.orm.session import sessionmaker Session=sessionmaker(engine) db_session=Session() ret=db_session.query(User).filter_by(id="2").delete() print(ret) db_session.commit() db_session.close()

 ************************************************************************************************************************

多表关联：主外键关联

from sqlalchemy.ext.declarative import declarative_base from sqlalchemy.engine import create_engine from sqlalchemy.orm.session import Session from sqlalchemy.orm import relationship from sqlalchemy import Column,Integer,String,ForeignKey #创建一个数据表的继承基类
Base=declarative_base() #创建一个数据库连接
engine=create_engine("mysql+pymysql://root:root1234@127.0.0.1:3306/db_unv?charset=utf8") #创建一个会话
db_session=Session(engine) class Student(Base): __tablename__="student" id=Column(Integer,primary_key=True) name=Column(String(32),index=True) school_id=Column(Integer,ForeignKey("school.id"))   #外键
    stu2sch=relationship("School",backref='sch2stu')    # school反向解析student关键字


class School(Base): __tablename__="school" id = Column(Integer, primary_key=True) name = Column(String(32), index=True) Base.metadata.create_all(engine)

 多表的数据添加：

from creat_table import engine,School,Student from sqlalchemy.orm.session import sessionmaker session=sessionmaker(engine) db_session=session() # stu_obj=Student(name="凯文",stu2sch=School(name="麻省理工")) #反向添加数据
sch_obj=School(name="常青藤大学",sch2stu=[Student(name="胡柯"),Student(name="徐素")])    #正向添加


# db_session.add(stu_obj)
db_session.add(sch_obj) db_session.commit() db_session.close()

 多表数据的更新和删除：

from creat_table import School,Student,engine from sqlalchemy.orm.session import sessionmaker Session=sessionmaker(engine) db_session=Session() # stu_obj=db_session.query(Student).filter(Student.name=="徐菲菲").first() # print(stu_obj.school_id) # # db_session.query(Student).filter(Student.id==stu_obj.id).update({"school_id":2})
sch_obj=db_session.query(School).filter(School.name=="麻省理工").first() # ret=db_session.query(Student).filter(Student.school_id==sch_obj.id).update({"school_id":3})
db_session.query(Student).filter(Student.school_id==sch_obj.id).delete() db_session.commit() db_session.close()