如何在使用sqlalchemy时选择特定列？

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

Base = declarative_base()

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

engine = create_engine('sqlite:///example.db')
Session = sessionmaker(bind=engine)
session = Session()

# 选择特定列
result = session.query(User.name, User.age).all()
for row in result:
    print(row.name, row.age)

result = session.query(User.name.label('username'), User.age.label('userage')).all()
for row in result:
    print(row.username, row.userage)

from sqlalchemy import func

result = session.query(func.count(User.id), User.name).group_by(User.name).all()
for row in result:
    print(row[0], row[1])

from sqlalchemy.orm import aliased

UserAlias = aliased(User)
result = session.query(UserAlias.name, UserAlias.age).filter(UserAlias.age > 25).all()
for row in result:
    print(row.name, row.age)

class User(Base):
    __tablename__ = 'users'
    id = Column(Integer, primary_key=True)
    name = Column(String)
    age = Column(Integer)  # 确保定义了 age 列

result = session.query(User.name, User.age).filter(User.age > 30).all()
if not result:
    print("No users found with age greater than 30")