三十二：数据库之SQLAlchemy.query函数可查询的数据和聚合函数

准备工作

from sqlalchemy import create_engine, Column, Integer, String, Float
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

# 数据库信息
host = '127.0.0.1'
port = '3306'
database = 'db_to_sqlalchemy'
username = 'root'
password = '123456'

# 数据库类型+连接数据库的插件，这里使用的pymysql
DB_URI = f'mysql+pymysql://{username}:{password}@{host}:{port}/{database}'

engine = create_engine(DB_URI)  # 创建引擎
Base = declarative_base(engine)  # 使用declarative_base创建基类
session = sessionmaker(engine)()


class Article(Base):
    __tablename__ = 'article'
    id = Column(Integer, primary_key=True, autoincrement=True)
    title = Column(String(50), nullable=False)
    price = Column(Float, nullable=Float)

    def __repr__(self):
        return f'Article(title): {self.title}、Article(price): {self.price}'


Base.metadata.create_all()  # 创建数据库

# 造测试数据
import random

for x in range(6):
    article = Article(title=f'title{x}', price=random.randint(1, 100))
    session.add(article)
session.commit()