sqlalchemy中的group by和count

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('数据库连接字符串')
Session = sessionmaker(bind=engine)
session = Session()

# 定义数据模型
Base = declarative_base()

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

# 查询每个年龄段的用户数量
result = session.query(User.age, func.count(User.id)).group_by(User.age).all()

for age, count in result:
    print(f"年龄段：{age}，用户数量：{count}")

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('数据库连接字符串')
Session = sessionmaker(bind=engine)
session = Session()

# 定义数据模型
Base = declarative_base()

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

# 统计用户数量
count = session.query(func.count(User.id)).scalar()
print(f"用户数量：{count}")