关于python:python-sqlalchemy-pg

from sqlalchemy import Column, String, create_engine, Integer, Textfrom sqlalchemy.orm import sessionmakerfrom sqlalchemy.ext.declarative import declarative_baseimport 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'     # 表的构造:    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))  # 初始化数据库连贯:engine = create_engine('postgres://postgres:123123@localhost:5432/postgres')  # 用户名:明码@localhost:端口/数据库名 # 创立DBSession类型:DBSession = sessionmaker(bind=engine) def createTable():    # 创立表    Base.metadata.create_all(engine)  def insertData():    # 插入操作    # 创立会话    session = DBSession()    # 创立新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)    # 增加到session:    session.add(new_user)    # 提交即保留到数据库:    session.commit()    # 敞开session:    session.close() def selectData():    # 查问操作    # 创立Session    session = DBSession()    # 创立Query查问，filter是where条件，最初调用one()返回惟一行，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()  # 敞开Session def updateData():    # 更新操作    session = DBSession()  # 创立会话    users = session.query(User).filter_by(name="hsh4").first()  # 查问条件    users.id_number = "abcd"  # 更新操作    session.add(users)  # 增加到会话    session.commit()  # 提交即保留到数据库    session.close()  # 敞开会话 def deleteData():    # 删除操作    session = DBSession()  # 创立会话    delete_users = session.query(User).filter(User.id == "1").first()    if delete_users:        session.delete(delete_users)        session.commit()    session.close()  # 敞开会话 def dropTable():    # 删除表    session = DBSession()  # 创立会话    session.execute('drop table users')    session.commit()    session.close()  # createTable()# insertData()# selectData()# updateData()# deleteData()