sqlalchemy相关知识
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1 #!/usr/bin/env python3.5 2 # -*- coding:utf8 -*- 3 # 多对多关联 4 from sqlalchemy import Table, Column, Integer, ForeignKey,String,create_engine,and_,or_,func 5 from sqlalchemy.orm import relationship,sessionmaker 6 from sqlalchemy.ext.declarative import declarative_base 7 Base = declarative_base() #生成一个SqlORM 基类 8 engine = create_engine("mysql+pymysql://python:123456@192.168.1.190:3306/python",echo=True) 9 # 1、创建一个关联表,关联两个对象 组和主机 10 Host2Group = Table(\'host_2_group\',Base.metadata, 11 Column(\'host_id\',ForeignKey(\'hosts.id\'),primary_key=True), 12 Column(\'group_id\',ForeignKey(\'group.id\'),primary_key=True), 13 ) 14 15 class Host(Base): 16 __tablename__ = \'hosts\' 17 id = Column(Integer,primary_key=True,autoincrement=True) 18 hostname = Column(String(64),unique=True,nullable=False) 19 ip_addr = Column(String(128),unique=True,nullable=False) 20 port = Column(Integer,default=22) 21 groups = relationship("Group", 22 secondary=Host2Group, # 指定中间表的实例 23 backref =\'host_list\') # backref参数则对关系提供反向引用的声明。 24 def __repr__(self): 25 return "<id =%s,hostname=%s,ip_addr =%s>"%\\ 26 (self.id, 27 self.hostname, 28 self.ip_addr) 29 class Group(Base): 30 __tablename__ ="group" 31 id = Column(Integer,primary_key=True) 32 name = Column(String(64),unique=True,nullable=False) 33 def __repr__(self): 34 return "<group_id =%s,group_name=%s>"%\\ 35 (self.id, 36 self.name) 37 38 39 Base.metadata.create_all(engine) #创建所有表结构 40 # 41 if __name__ == \'__main__\': 42 SessionCls = 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class,不是实例 43 session = SessionCls() # 这才是连接的实例 44 # g1 = Group(name = "g1") 45 # g2 = Group(name = "g2") 46 # g3 = Group(name = "g3") 47 # g4 = Group(name = "g4") 48 \'\'\' 49 h1 = Host(hostname=\'h1\',ip_addr=\'192.168.2.242\',port = 2000) 50 h2 = Host(hostname=\'h2\',ip_addr=\'192.168.2.243\',port=20000) 51 h3 = Host(hostname=\'h3\',ip_addr=\'192.168.2.244\',port=20000) 52 session.add_all([h1,h2,h3]) 53 \'\'\' 54 # 关联主机 55 # 找组 56 g1 = session.query(Group).first() 57 # groups = session.query(Group).all() 58 # h1 = session.query(Host).filter(Host.hostname == "h1").first() 59 # 找主机 60 h2 = session.query(Host).filter(Host.hostname == "h2").first() 61 # h3 = session.query(Host).filter(Host.hostname == "h3").first() 62 # # h1.groups = groups 63 # # h1.groups.pop() 64 # 关联,使一个主机属于多个组 65 # h2.groups = groups[1:-1] 66 # 查询 67 print("======>",h2.groups) 68 print("=====>",g1.host_list) 69 # update 70 # obj = session.query(Host).filter(Host.hostname == "test_localhost").first() 71 # print("++>",obj) 72 # #obj.hostname = "test_localhost" # 更改 73 # session.delete(obj) 74 # objs = session.query(Host).filter(and_(Host.hostname.like("ubun%"),Host.port > 20)).all() 75 # print("+++>",objs) 76 77 78 session.commit()
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