SQLAlchemy-简单例子

from sqlalchemy import create_engine, Column, Integer, String, DateTime, Float, func

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

# 连接数据库字符串
DB_URI = "mysql://root:123456@127.0.0.1/pyDemo"

engine = create_engine(DB_URI)
# 判断是否连接成功
engine.connect()


# 创建ORM
Base = declarative_base(engine)

# 创建回话
session = sessionmaker(engine)()
class Article(Base):
    # 表名字
    __tablename__ = 'Article'
    # 列
    id = Column(Integer, primary_key=True, autoincrement=True)
    # read_count = Column(Integer, default=0)
    title = Column(String(50), default='1111')
    price = Column(Float, nullable=False)
    def __repr(self):
        return "<Article(title%s)>" % self.title
# 生成实体
# Base.metadata.drop_all()
# Base.metadata.create_all()
import random
# article = Article(price=random.randint(50, 100))
# session.add(article)
# session.commit()
# # 查询第一条数据
# article = session.query(Article).first()
# # 更新当前数据
# article.title = "123"
# session.commit()
# 批量添加数据
# for x in range(6):
#     article = Article(title='title%s' % x, price=random.randint(50, 100))
#     session.add(article)
#     session.commit()
# query使用
# 查询所有的
articles = session.query(Article).all()
print(articles)
# 模型中的属性
articles = session.query(Article.title, Article.price).all()
print(articles)
# 聚合函数
# 行数
result = session.query(func.count(Article.id)).first()
print(result[0])
# 平均值
result = session.query(func.avg(Article.price)).first()
print(result[0])
# 最大值
result = session.query(func.max(Article.price)).first()
print(result[0])
# 最小值
result = session.query(func.min(Article.price)).first()
print(result[0])
# 求和
result = session.query(func.sum(Article.price)).first()
print(result[0])