flask SQLAlchemy 增删改查

models.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
@file: orm1.py
@time: 2019/03/13
"""
#!/usr/bin/env python
# -*- coding:utf-8 -*-
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()

# ##################### 单表示例 #########################
class Users(Base):
    __tablename__ = 'users'
    id = Column(Integer, primary_key=True)
    # index 普通索引
    name = Column(String(32), index=True)
    age = Column(Integer, default=18)
    email = Column(String(32), unique=True)
    ctime = Column(DateTime, default=datetime.datetime.now)
    extra = Column(Text, nullable=True)

    __table_args__ = (
        # 联合唯一索引
        # UniqueConstraint('id', 'name', name='uix_id_name'),
        # 普通索引
        # Index('ix_id_name', 'name', 'extra'),
    )


class Hosts(Base):
    __tablename__ = 'hosts'
    id = Column(Integer, primary_key=True)
    name = Column(String(32), index=True)
    ctime = Column(DateTime, default=datetime.datetime.now)


# ##################### 一对多示例 #########################
class Hobby(Base):
    __tablename__ = 'hobby'
    id = Column(Integer, primary_key=True)
    caption = Column(String(50), default='篮球')


class Person(Base):
    __tablename__ = 'person'
    nid = Column(Integer, primary_key=True)
    name = Column(String(32), index=True, nullable=True)
    # hobby为表名（不是类名）
    hobby_id = Column(Integer, ForeignKey("hobby.id"))
    # 与生成表结构无关，仅用于查询方便
    hobby = relationship("Hobby", backref='pers')


# ##################### 多对多示例 #########################

class Server2Group(Base):
    __tablename__ = 'server2group'
    id = Column(Integer, primary_key=True, autoincrement=True)
    server_id = Column(Integer, ForeignKey('server.id'))
    group_id = Column(Integer, ForeignKey('group.id'))


class Group(Base):
    __tablename__ = 'group'
    id = Column(Integer, primary_key=True)
    name = Column(String(64), unique=True, nullable=False)

    # 与生成表结构无关，仅用于查询方便
    servers = relationship('Server', secondary='server2group', backref='groups')


class Server(Base):
    __tablename__ = 'server'
    id = Column(Integer, primary_key=True, autoincrement=True)
    hostname = Column(String(64), unique=True, nullable=False)


def init_db():
    """
    根据类创建数据库表
    :return:
    """
    engine = create_engine(
        "mysql+pymysql://root:[email protected]:3306/s6?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.create_all(engine)


def drop_db():
    """
    根据类删除数据库表
    :return:
    """
    engine = create_engine(
        "mysql+pymysql://root:[email protected]:3306/s6?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()

  https://www.cnblogs.com/wupeiqi/p/8259356.html

查询：

from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from orm1 import Users

# 1.创建连接池
engine = create_engine("mysql+pymysql://root:[email protected]:3306/s6", max_overflow=0, pool_size=5)
Session = sessionmaker(bind=engine)

# 2.从连接池中，获取数据连接
session = Session()

# 查所有数据
user_list = session.query(Users).all()
for i in user_list:
    print(i.name)
    print(i.ctime)
 
#  查询符合条件的所有数据对象 （可加.all()）
users = session.query(Users).filter(Users.name=="alex1")
#users = session.query(Users).filter_by(name='alex1')
for ii in users:
    print(ii)
    print(ii.name)

#  查询符合条件的第一个数据对象
users = session.query(Users).filter(Users.name=="alex1").first()
#users = session.query(Users).filter_by(name='alex1').first()
print(users.name)

#查询多个字段
users = session.query(Users.email.label('xx'), Users.name).all()
for item in users:
    print(item)
    print(item.xx)
print(users)

# 多条件查询
ret = session.query(Users).filter(text("name=name and email=email")).params(name='alex1',email='[email protected]').all()
print(type(ret),ret)  #list
print(ret[0].name)

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
@file: s3操作.py
@time: 2019/03/13
"""
from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from orm1 import Users

# 1.创建连接池
engine = create_engine("mysql+pymysql://root:***@127.0.0.1:3306/s6", max_overflow=0, pool_size=5)
Session = sessionmaker(bind=engine)

# 2.从连接池中，获取数据连接
session = Session()

# 3.执行ORM操作
# 增加
# obj1 = Users(name="alex1")
# session.add(obj1)
# # 提交事务
# session.commit()

#批量增加
# obj1 = Users(name="alex1")
# session.add_all([
#     Users(name="alex3", email="[email protected]"),
#     Users(name="alex4", email="[email protected]")
# ])

# 查所有数据
# user_list = session.query(Users).all()
# for i in user_list:
#     print(i.name)
#     print(i.ctime)

#  条件查询
# users = session.query(Users).filter(Users.id>2)
# for ii in users:
#     print(ii.name)
#     print(ii.ctime)

users = session.query(Users.email.label('xx'),Users.name).all()
for item in users:
    print(item.xx)
print(users)

#  删除
# session.query(Users).filter(Users.id==2).delete()

# 修改
# session.query(Users).filter(Users.id==3).update({"name":"yangtao"})

# 提交事务
session.commit()

# 4.将连接放回连接池
session.close()

常用操作：

filter中有多个查询条件，查询条件为and关系

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()

注意in后面需跟下划线

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()

~ 非  除了id为1、3、4以外的用户

ret = session.query(Users).filter(~Users.id.in_([1,3,4])).all()

and和or嵌套

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()

排序

ret = session.query(Users).order_by(Users.name.desc()).all()

# 优先按照name倒序排列；若有重名，重名的按照id升序排列
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()

# 根据用户名进行分组，然后取最大id、最小id和id的和
ret = session.query(
    func.max(Users.id),
    func.sum(Users.id),
    func.min(Users.id)).group_by(Users.name).all()

# 根据用户名分组，求每组中用户最小id大于2的数据（符合条件的每组最大id，最小id，id的和）
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

只有内连接和左连接，没有right join，但可以调换位置达到右连接效果isouter=True标记左连接 ；
join第二个参数可以指定关联条件

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()

反向、正向查询

方法二：

在model中添加relationship字段（在数据库中不生产字段）

反向、正向增加

方法一：
person = Person(name='张九', hobby=Hobby(caption='姑娘'))
session.add(person)

方法二：
hb = Hobby(caption='人妖')
hb.pers = [Person(name='文飞'), Person(name='博雅')]
session.add(hb)

session.commit()

# 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]

# 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()