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SqlAlchemy
SQLAlchemy是Python编程语言下的一款ORM框架，该框架建立在数据库API之上，使用关系对象映射进行数据库操作，简言之便是：将对象转换成SQL，然后使用数据API执行SQL并获取执行结果。
一、安装mysql
yum install -y mysql-server
二、
使用 ORM/Schema Type/SQL Expression Language/Engine/ConnectionPooling/Dialect 所有组件对数据进行操作。根据类创建对象，对象转换成SQL，执行SQL。
1.创建表
#!/usr/bin/env python # -*- coding:utf-8 -*- from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index from sqlalchemy.orm import sessionmaker, relationship from sqlalchemy import create_engine engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/t1", max_overflow=5) Base = declarative_base() # 创建单表 class Users(Base): __tablename__ = ‘users‘ id = Column(Integer, primary_key=True) name = Column(String(32)) extra = Column(String(16)) __table_args__ = ( UniqueConstraint(‘id‘, ‘name‘, name=‘uix_id_name‘), Index(‘ix_id_name‘, ‘name‘, ‘extra‘), ) # 一对多 class Favor(Base): __tablename__ = ‘favor‘ nid = Column(Integer, primary_key=True) caption = Column(String(50), default=‘red‘, unique=True) class Person(Base): __tablename__ = ‘person‘ nid = Column(Integer, primary_key=True) name = Column(String(32), index=True, nullable=True) favor_id = Column(Integer, ForeignKey("favor.nid")) # 多对多 class Group(Base): __tablename__ = ‘group‘ id = Column(Integer, primary_key=True) name = Column(String(64), unique=True, nullable=False) port = Column(Integer, default=22) class Server(Base): __tablename__ = ‘server‘ id = Column(Integer, primary_key=True, autoincrement=True) hostname = Column(String(64), unique=True, nullable=False) class ServerToGroup(Base): __tablename__ = ‘servertogroup‘ nid = Column(Integer, primary_key=True, autoincrement=True) server_id = Column(Integer, ForeignKey(‘server.id‘)) group_id = Column(Integer, ForeignKey(‘group.id‘)) def init_db(): Base.metadata.create_all(engine) def drop_db(): Base.metadata.drop_all(engine)
2、操作表
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 from sqlalchemy.ext.declarative import declarative_base 4 from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index 5 from sqlalchemy.orm import sessionmaker, relationship 6 from sqlalchemy import create_engine 7 8 engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/t1", max_overflow=5) 9 10 Base = declarative_base() 11 12 # 创建单表 13 class Users(Base): 14 __tablename__ = ‘users‘ 15 id = Column(Integer, primary_key=True) 16 name = Column(String(32)) 17 extra = Column(String(16)) 18 19 __table_args__ = ( 20 UniqueConstraint(‘id‘, ‘name‘, name=‘uix_id_name‘), 21 Index(‘ix_id_name‘, ‘name‘, ‘extra‘), 22 ) 23 24 def __repr__(self): 25 return "%s-%s" %(self.id, self.name) 26 27 # 一对多 28 class Favor(Base): 29 __tablename__ = ‘favor‘ 30 nid = Column(Integer, primary_key=True) 31 caption = Column(String(50), default=‘red‘, unique=True) 32 33 def __repr__(self): 34 return "%s-%s" %(self.nid, self.caption) 35 36 class Person(Base): 37 __tablename__ = ‘person‘ 38 nid = Column(Integer, primary_key=True) 39 name = Column(String(32), index=True, nullable=True) 40 favor_id = Column(Integer, ForeignKey("favor.nid")) 41 # 与生成表结构无关，仅用于查询方便 42 favor = relationship("Favor", backref=‘pers‘) 43 44 # 多对多 45 class ServerToGroup(Base): 46 __tablename__ = ‘servertogroup‘ 47 nid = Column(Integer, primary_key=True, autoincrement=True) 48 server_id = Column(Integer, ForeignKey(‘server.id‘)) 49 group_id = Column(Integer, ForeignKey(‘group.id‘)) 50 group = relationship("Group", backref=‘s2g‘) 51 server = relationship("Server", backref=‘s2g‘) 52 53 class Group(Base): 54 __tablename__ = ‘group‘ 55 id = Column(Integer, primary_key=True) 56 name = Column(String(64), unique=True, nullable=False) 57 port = Column(Integer, default=22) 58 # group = relationship(‘Group‘,secondary=ServerToGroup,backref=‘host_list‘) 59 60 61 class Server(Base): 62 __tablename__ = ‘server‘ 63 64 id = Column(Integer, primary_key=True, autoincrement=True) 65 hostname = Column(String(64), unique=True, nullable=False) 66 67 68 69 70 def init_db(): 71 Base.metadata.create_all(engine) 72 73 74 def drop_db(): 75 Base.metadata.drop_all(engine) 76 77 78 Session = sessionmaker(bind=engine) 79 session = Session()
- 增
obj = Users(name="alex0", extra=‘sb‘) session.add(obj) session.add_all([ Users(name="alex1", extra=‘sb‘), Users(name="alex2", extra=‘sb‘), ]) session.commit()
- 删
session.query(Users).filter(Users.id > 2).delete()
session.commit()
- 改
session.query(Users).filter(Users.id > 2).update({"name" : "099"})
session.query(Users).filter(Users.id > 2).update({Users.name: Users.name + "099"}, synchronize_session=False)
session.query(Users).filter(Users.id > 2).update({"num": Users.num + 1}, synchronize_session="evaluate")
session.commit()
- 查
ret = session.query(Users).all() ret = session.query(Users.name, Users.extra).all() ret = session.query(Users).filter_by(name=‘alex‘).all() ret = session.query(Users).filter_by(name=‘alex‘).first()
- 其他
# 条件 ret = session.query(Users).filter_by(name=‘alex‘).all() ret = session.query(Users).filter(Users.id > 1, Users.name == ‘eric‘).all() ret = session.query(Users).filter(Users.id.between(1, 3), Users.name == ‘eric‘).all() ret = session.query(Users).filter(Users.id.in_([1,3,4])).all() ret = session.query(Users).filter(~Users.id.in_([1,3,4])).all() ret = session.query(Users).filter(Users.id.in_(session.query(Users.id).filter_by(name=‘eric‘))).all() from sqlalchemy import and_, or_ ret = session.query(Users).filter(and_(Users.id > 3, Users.name == ‘eric‘)).all() ret = session.query(Users).filter(or_(Users.id < 2, Users.name == ‘eric‘)).all() ret = session.query(Users).filter( or_( Users.id < 2, and_(Users.name == ‘eric‘, Users.id > 3), Users.extra != "" )).all() # 通配符 ret = session.query(Users).filter(Users.name.like(‘e%‘)).all() ret = session.query(Users).filter(~Users.name.like(‘e%‘)).all() # 限制 ret = session.query(Users)[1:2] # 排序 ret = session.query(Users).order_by(Users.name.desc()).all() ret = session.query(Users).order_by(Users.name.desc(), Users.id.asc()).all() # 分组 from sqlalchemy.sql import func ret = session.query(Users).group_by(Users.extra).all() ret = session.query( func.max(Users.id), func.sum(Users.id), func.min(Users.id)).group_by(Users.name).all() ret = session.query( func.max(Users.id), func.sum(Users.id), func.min(Users.id)).group_by(Users.name).having(func.min(Users.id) >2).all() # 连表 ret = session.query(Users, Favor).filter(Users.id == Favor.nid).all() ret = session.query(Person).join(Favor).all() ret = session.query(Person).join(Favor, isouter=True).all() # 组合 q1 = session.query(Users.name).filter(Users.id > 2) q2 = session.query(Favor.caption).filter(Favor.nid < 2) ret = q1.union(q2).all() q1 = session.query(Users.name).filter(Users.id > 2) q2 = session.query(Favor.caption).filter(Favor.nid < 2) ret = q1.union_all(q2).all()
SqlAlchemy
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