ORM框架SQLAlchemy操作表：
表结构和数据库连接：
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：
1 obj = Users(name="alex0", extra='sb')
2 session.add(obj)
3 session.add_all([
4 Users(name="alex1", extra='sb'),
5 Users(name="alex2", extra='sb'),
6 ])
7 session.commit()
查：
1 ret = session.query(Users).all()
2 ret = session.query(Users.name, Users.extra).all()
3 ret = session.query(Users).filter_by(name='alex').all()
4 ret = session.query(Users).filter_by(name='alex').first()
5
6 ret = session.query(Users).filter(text("id<:value and name=:name")).params(value=224, name='fred').order_by(User.id).all()
7
8 ret = session.query(Users).from_statement(text("SELECT * FROM users where name=:name")).params(name='ed').all()
删：先查后删
1 session.query(Users).filter(Users.id > 2).delete()
2 session.commit()
改：先查后改
1 session.query(Users).filter(Users.id > 2).update({"name" : "099"})
2 session.query(Users).filter(Users.id > 2).update({Users.name: Users.name + "099"}, synchronize_session=False)
3 session.query(Users).filter(Users.id > 2).update({"num": Users.num + 1}, synchronize_session="evaluate")
4 session.commit()
其他：
1 # 条件
2 ret = session.query(Users).filter_by(name='alex').all()
3 ret = session.query(Users).filter(Users.id > 1, Users.name == 'eric').all()
4 ret = session.query(Users).filter(Users.id.between(1, 3), Users.name == 'eric').all()
5 ret = session.query(Users).filter(Users.id.in_([1,3,4])).all()
6 ret = session.query(Users).filter(~Users.id.in_([1,3,4])).all()
7 ret = session.query(Users).filter(Users.id.in_(session.query(Users.id).filter_by(name='eric'))).all()
8 from sqlalchemy import and_, or_
9 ret = session.query(Users).filter(and_(Users.id > 3, Users.name == 'eric')).all()
10 ret = session.query(Users).filter(or_(Users.id < 2, Users.name == 'eric')).all()
11 ret = session.query(Users).filter(
12 or_(
13 Users.id < 2,
14 and_(Users.name == 'eric', Users.id > 3),
15 Users.extra != ""
16 )).all()
17
18
19 # 通配符
20 ret = session.query(Users).filter(Users.name.like('e%')).all()
21 ret = session.query(Users).filter(~Users.name.like('e%')).all()
22
23 # 限制
24 ret = session.query(Users)[1:2]
25
26 # 排序
27 ret = session.query(Users).order_by(Users.name.desc()).all()
28 ret = session.query(Users).order_by(Users.name.desc(), Users.id.asc()).all()
29
30 # 分组
31 from sqlalchemy.sql import func
32
33 ret = session.query(Users).group_by(Users.extra).all()
34 ret = session.query(
35 func.max(Users.id),
36 func.sum(Users.id),
37 func.min(Users.id)).group_by(Users.name).all()
38
39 ret = session.query(
40 func.max(Users.id),
41 func.sum(Users.id),
42 func.min(Users.id)).group_by(Users.name).having(func.min(Users.id) >2).all()
43
44 # 连表
45
46 ret = session.query(Users, Favor).filter(Users.id == Favor.nid).all()
47
48 ret = session.query(Person).join(Favor).all()
49
50 ret = session.query(Person).join(Favor, isouter=True).all()
51
52
53 # 组合
54 q1 = session.query(Users.name).filter(Users.id > 2)
55 q2 = session.query(Favor.caption).filter(Favor.nid < 2)
56 ret = q1.union(q2).all()
57
58 q1 = session.query(Users.name).filter(Users.id > 2)
59 q2 = session.query(Favor.caption).filter(Favor.nid < 2)
60 ret = q1.union_all(q2).all()
