标签：sch sql lse end str iso def 文件的 sel
今日所学内容：
一、SQLAlchemy
二、创建表
三、操作表
一、SQLAlchemy?
二、创建表
导入模块
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
创建引擎
engine = create_engine("mysql+pymysql://root:000000@127.0.0.1:3306/t1?charset=utf8", max_overflow=5)
实例化Base类
Base = declarative_base()
创建单表
class Users(Base):
__tablename__ = ‘users‘
id = Column(Integer, primary_key=True)
name = Column(VARCHAR(32))
extra = Column(VARCHAR(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(VARCHAR(50), default=‘red‘, unique=True)
class Person(Base):
__tablename__ = ‘person‘
nid = Column(Integer, primary_key=True)
name = Column(VARCHAR(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(VARCHAR(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(VARCHAR(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 create_db():
Base.metadata.create_all(engine)
def drop_db():
Base.metadata.drop_all(engine)
# create_db();
# drop_db();
三、操作表
导入模块
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
创建引擎
engine = create_engine("mysql+pymysql://root:000000@127.0.0.1:3306/t1?charset=utf8", max_overflow=5)
实例化Base类
Base = declarative_base()
创建单表
class Users(Base):
__tablename__ = ‘users‘
id = Column(Integer, primary_key=True)
name = Column(VARCHAR(32))
extra = Column(VARCHAR(16))
__table_args__ = (
UniqueConstraint(‘id‘, ‘name‘, name=‘uix_id_name‘),
Index(‘ix_id_name‘, ‘name‘, ‘extra‘),
)
def __repr__(self):
return "%s-%s" %(self.id, self.name)
一对多
class Favor(Base):
__tablename__ = ‘favor‘
nid = Column(Integer, primary_key=True)
caption = Column(VARCHAR(50), default=‘red‘, unique=True)
def __repr__(self):
return "%s-%s" %(self.nid, self.caption)
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"))
与生成表结构无关，仅用于查询方便
favor = relationship("Favor", backref=‘pers‘)
多对多
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‘))
group = relationship("Group", backref=‘s2g‘)
server = relationship("Server", backref=‘s2g‘)
class Group(Base):
__tablename__ = ‘group‘
id = Column(Integer, primary_key=True)
name = Column(String(64), unique=True, nullable=False)
port = Column(Integer, default=22)
# group = relationship(‘Group‘,secondary=ServerToGroup,backref=‘host_list‘)
class Server(Base):
__tablename__ = ‘server‘
id = Column(Integer, primary_key=True, autoincrement=True)
hostname = Column(String(64), unique=True, nullable=False)
def create_db():
Base.metadata.create_all(engine)
def drop_db():
Base.metadata.drop_all(engine)
# create_db();
# drop_db();
Session = sessionmaker(bind=engine)
session = Session()
增加
增加一条数据
obj = Users(name="alex0", extra=‘sb‘)
session.add(obj)
增加多条数据
session.add_all([
Users(name="alex1", extra=‘sb‘),
Users(name="alex2", extra=‘sb‘),
])
session.commit()
删除
session.query(Users).filter(Users.id > 2).delete()
session.commit()
修改
session.query(Users).filter(Users.id > 2).update({"name" : "099"})
session.commit()
查询
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()
其它
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 limit
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.min(Users.id)).group_by(Users.name).all()
ret = session.query(
func.max(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()
标签：sch sql lse end str iso def 文件的 sel
原文地址：https://www.cnblogs.com/Chinesehan/p/11047152.html
