安装psycopg2和sqlalchemy模块：

pip install sqlalchemy
pip install psycopg2

 测试代码：

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

# 创建对象的基类:
Base = declarative_base()


# 定义User对象:
class User(Base):
    # 表的名字:
    __tablename__ = 'users'

    # 表的结构:
    id = Column(Integer, autoincrement=True, primary_key=True, unique=True, nullable=False)
    name = Column(String(50), nullable=False)
    sex = Column(String(4), nullable=False)
    nation = Column(String(20), nullable=False)
    birth = Column(String(8), nullable=False)
    id_address = Column(Text, nullable=False)
    id_number = Column(String(18), nullable=False)
    creater = Column(String(32))
    create_time = Column(String(20), nullable=False)
    updater = Column(String(32))
    update_time = Column(String(20), nullable=False, default=time.strftime("%Y-%m-%d %H:%M:%S", time.localtime()),
                         onupdate=time.strftime("%Y-%m-%d %H:%M:%S", time.localtime()))
    comment = Column(String(200))


# 初始化数据库连接:
engine = create_engine('postgres://postgres:123123@localhost:5432/postgres')  # 用户名:密码@localhost:端口/数据库名

# 创建DBSession类型:
DBSession = sessionmaker(bind=engine)

def createTable():
    # 创建表
    Base.metadata.create_all(engine)


def insertData():
    # 插入操作
    # 创建会话
    session = DBSession()
    # 创建新User对象:
    local_time = time.strftime("%Y-%m-%d %H:%M:%S", time.localtime())
    new_user = User(name='hsh4', sex='男', nation='汉', birth='19991012', id_address='广州大学', id_number='441242142142',
                    create_time=local_time)
    # 添加到session:
    session.add(new_user)
    # 提交即保存到数据库:
    session.commit()
    # 关闭session:
    session.close()

def selectData():
    # 查询操作
    # 创建Session
    session = DBSession()
    # 创建Query查询，filter是where条件，最后调用one()返回唯一行，如果调用all()则返回所有行:
    user = session.query(User).filter(User.id == '1' and User.name == 'hsh4').one()
    print('name:', user.name)
    print('id_address:', user.id_address)
    session.close()  # 关闭Session

def updateData():
    # 更新操作
    session = DBSession()  # 创建会话
    users = session.query(User).filter_by(name="hsh4").first()  # 查询条件
    users.id_number = "abcd"  # 更新操作
    session.add(users)  # 添加到会话
    session.commit()  # 提交即保存到数据库
    session.close()  # 关闭会话

def deleteData():
    # 删除操作
    session = DBSession()  # 创建会话
    delete_users = session.query(User).filter(User.id == "1").first()
    if delete_users:
        session.delete(delete_users)
        session.commit()
    session.close()  # 关闭会话

def dropTable():
    # 删除表
    session = DBSession()  # 创建会话
    session.execute('drop table users')
    session.commit()
    session.close()


# createTable()
# insertData()
# selectData()
# updateData()
# deleteData()
# dropTable()

 更多详细用法请参考官方文档：PostgreSQL--SQLALchemy Documentation

以及ORM相关知识：ORM知识介绍