select与聚合目标不同的SQLAlchemy group_by

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

# 创建数据库连接
engine = create_engine('mysql://username:password@localhost/db_name')
Session = sessionmaker(bind=engine)
session = Session()

# 创建映射类
Base = declarative_base()

class User(Base):
    __tablename__ = 'users'
    id = Column(Integer, primary_key=True)
    name = Column(String(50))
    age = Column(Integer)

# 查询年龄大于等于30的用户，并按照年龄进行分组，计算每个年龄组的用户数量
result = session.query(User.age, func.count(User.id)).\
    filter(User.age >= 30).\
    group_by(User.age).all()

# 输出结果
for age, count in result:
    print(f"年龄：{age}，用户数量：{count}")