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四十三：数据库之SQLAlchemy之group_by和having子句

时间：2021-07-01 10:21:17 帮助过：9人阅读

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker, relationship, backref

# 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 User(Base):
__tablename__ = ‘user‘
id = Column(Integer, primary_key=True, autoincrement=True)
username = Column(String(50), nullable=False)
age = Column(Integer, default=0)
gender = Column(String(20), default=‘male‘)

Base.metadata.drop_all() # 删除所有表
Base.metadata.create_all() # 创建表

user1 = User(username=‘user1‘, age=20, gender=‘male‘)
user2 = User(username=‘user2‘, age=21, gender=‘female‘)
user3 = User(username=‘user3‘, age=20, gender=‘secret‘)
user4 = User(username=‘user4‘, age=26, gender=‘male‘)
user5 = User(username=‘user5‘, age=19, gender=‘female‘)
session.add_all([user1, user2, user3, user4, user5])
session.commit()

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