flask的SQLAlchemy
"""
安装：
pip install sqlalchemy
"""
models.py
# pip install sqlalchemy
import datetime
from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, Text, ForeignKey, DateTime, UniqueConstraint, Index
from sqlalchemy.orm import relationship
Base = declarative_base()
class Users(Base):
__tablename__ = 'users' # 数据库表名称
id = Column(Integer, primary_key=True) # id 主键
name = Column(String(32), index=True, nullable=False) # name列，索引，不可为空
age = Column(Integer)
#email = Column(String(32), unique=True)
#datetime.datetime.now#不能加括号，加了括号，以后永远是当前时间
#ctime = Column(DateTime, default=datetime.datetime.now)
#extra = Column(Text, nullable=True)
__table_args__ = (
# UniqueConstraint('id', 'name', name='uix_id_name'), #联合唯一
# Index('ix_id_name', 'name', 'email'), #索引
)
def __repr__(self): # 作用类似于__str__, 但是__repr__的作用更加底层，__str__则打印不出来
return self.name
class Hobby(Base):
__tablename__ = "hobby"
id = Column(Integer, primary_key=True)
catption = Column(String(50), default="双色球")
class Person(Base):
__tablename__ = "person"
nid = Column(Integer, primary_key=True)
name = Column(String(32))
#hobby指的是tablename而不是Hobby类名，
hobby_id = Column(Integer,ForeignKey("hobby.id"))
# 跟数据库没有关系，不会新增加字段，只能用于快速的链表查询操作
#relationship的第一个参数，是类名，第二个参数backref，用于反向查询
hobby =relationship("Hobby", backref="pres")
def __repr__(self):
return self.name
# # 一个男孩可以喜欢多个女孩，一个女孩也可以喜欢多个男孩
class Boy2Girl(Base):
__tablename__ = "boy2girl"
id = Column(Integer, primary_key=True)
girl_id = Column(Integer,ForeignKey("girl.id"))
boy_id = Column(Integer,ForeignKey("boy.id"))
class Girl(Base):
__tablename__ = "girl"
id = Column(Integer,primary_key=True)
name = Column(String(100),nullable=False)
def __repr__(self):
return self.name
class Boy(Base):
__tablename__ = "boy"
id = Column(Integer, primary_key=True)
name = Column(String(100), nullable=False)
#secondary=boy2girl 中间表的表名
girl = relationship("Girl",secondary="boy2girl",backref = "boys")
def __repr__(self):
return self.name
def init_db():
"""
根据类创建数据库表
:return:
"""
engine = create_engine(
"mysql+pymysql://root:123456@127.0.0.1:3306/python13?charset=utf8",
#"什么数据库（mysql,orcal）+用什么取链接数据库（pymysql）://数据库用户名:密码@mysqlip:端口/数据库名？charset=字符集"
max_overflow=0, # 超过连接池大小外最多创建的连接
pool_size=5, # 连接池大小
pool_timeout=30, # 池中没有线程最多等待的时间，否则报错
pool_recycle=-1 # 多久之后对线程池中的线程进行一次连接的回收（重置）
)
Base.metadata.create_all(engine)
def drop_db():
"""
根据类删除数据库表
:return:
"""
engine = create_engine(
"mysql+pymysql://root:123456@127.0.0.1:3306/python13?charset=utf8",
max_overflow=0, # 超过连接池大小外最多创建的连接
pool_size=5, # 连接池大小
pool_timeout=30, # 池中没有线程最多等待的时间，否则报错
pool_recycle=-1 # 多久之后对线程池中的线程进行一次连接的回收（重置）
)
Base.metadata.drop_all(engine)
if __name__ == '__main__':
drop_db()
init_db()
orm的多对多
from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from models import Boy,Boy2Girl,Girl
engine = create_engine("mysql+pymysql://root:123456@127.0.0.1:3306/python13", max_overflow=0, pool_size=5)
Connection = sessionmaker(bind=engine)
#
# # 每次执行数据库操作时，都需要创建一个Connection
session = Connection()
#
#添加
session.add_all([
Boy(name="tank"),
Boy(name="sean"),
Girl(name="仓老师"),
Girl(name="小泽老师")
])
b2g = Boy2Girl(boy_id=1, girl_id=2)
session.add(b2g)
b2g = Boy2Girl(boy_id=2, girl_id=1)
session.add(b2g)
session.commit()
session.close()
# 正向插入
boy = Boy(name="alen")
boy.girl=[Girl(name="迪丽热巴"),Girl(name="三上悠亚")]
session.add(boy)
session.commit()
# 反向插入
girl = Girl(name="丹丹")
girl.boys=[Boy(name="吴彦祖"),Boy(name="鹿晗")]
session.add(girl)
session.commit()
# # 使用relationship的关系，正反向查
b = session.query(Boy).filter(Boy.name == "alen").first()
print(b.name)
print(b.girl)
# #反向查询
g = session.query(Girl).filter(Girl.name=="丹丹").first()
print(g.name)
print(g.boys)