SQLAlchemy ORM框架

连表操作

  • 一对多

    • 创建表 指定约束 ForeignKey

    
from sqlalchemy import create_engine
    
from sqlalchemy.ext.declarative import declarative_base
    
from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index
    
from sqlalchemy.orm import sessionmaker, relationship

engine = create_engine("mysql+pymysql://tuocigaoshou:Eb^BEF38E9FBC36CA775@111.204.117.99:3306/test", max_overflow=5)

Base = declarative_base()

# 一对多
    
class Group(Base):
    
    __tablename__ = "group"
    
    nid = Column(Integer, primary_key=True, autoincrement=True)
    
    caption = Column          # 组名

class User(Base):
    
    __tablename__ = "user"
    
    nid = Column(Integer, primary_key=True, autoincrement=True)
    
    username = Column(String(32))
    
    group_id = Column(Integer, ForeignKey("group.nid"))  # 外键

Base.metadata.create_all(engine)
    • 插入数据
    from sqlalchemy import create_engine
    
from sqlalchemy.ext.declarative import declarative_base
    
from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index
    
from sqlalchemy.orm import sessionmaker, relationship

engine = create_engine("mysql+pymysql://tuocigaoshou:Eb^BEF38E9FBC36CA775@111.204.117.99:3306/test", max_overflow=5)

Base = declarative_base()

# 单表
    
class Test(Base):
    
    __tablename__ = "test"
    
    nid = Column(Integer, primary_key=True, autoincrement=True)
    
    name = Column(String(32))

# 一对多
    
class Group(Base):
    
    __tablename__ = "group"
    
    nid = Column(Integer, primary_key=True, autoincrement=True)
    
    caption = Column(String(32))          # 组名

class User(Base):
    
    __tablename__ = "user"
    
    nid = Column(Integer, primary_key=True, autoincrement=True)
    
    username = Column(String(32))
    
    group_id = Column(Integer, ForeignKey("group.nid"))  # 外键

# Base.metadata.create_all(engine)    # 创建表
    
# Base.metadata.drop_all(engine)    # 删除表

Session = sessionmaker(bind=engine)
    
session = Session()

### 添加数据
    
# 向表中添加单条数据
    
session.add(Group("dba"))
    
session.add(Group("ddd"))

# 向表中添加多条数据
    
session.add_all(
    
    [
    
        User(username="a", group_id=1),
    
        User(username="b", group_id=2),
    
        User(username="c", group_id=1)
    
    ]
    
)

session.commit()
    • 查询数据

    
from sqlalchemy import create_engine
    
from sqlalchemy.ext.declarative import declarative_base
    
from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index
    
from sqlalchemy.orm import sessionmaker, relationship

engine = create_engine("mysql+pymysql://tuocigaoshou:Eb^BEF38E9FBC36CA775@111.204.117.99:3306/test", max_overflow=5)

Base = declarative_base()

### 创建表结构
    
# 单表
    
class Test(Base):
    
    __tablename__ = "test"
    
    nid = Column(Integer, primary_key=True, autoincrement=True)
    
    name = Column(String(32))

# 一对多
    
class Group(Base):
    
    __tablename__ = "group"
    
    nid = Column(Integer, primary_key=True, autoincrement=True)
    
    caption = Column(String(32))          # 组名

class User(Base):
    
    __tablename__ = "user"
    
    nid = Column(Integer, primary_key=True, autoincrement=True)
    
    username = Column(String(32))
    
    group_id = Column(Integer, ForeignKey("group.nid"))  # 外键

    # 与生成表结构无关，仅用于更方便的进行连表查询
    
    group = relationship("Group", backref="user")

    def __repr__(self):
    
        temp = "%s - %s - %s" % (self.nid, self.username, self.group_id)
    
        return temp

# Base.metadata.create_all(engine)    # 创建表
    
# Base.metadata.drop_all(engine)    # 删除表

Session = sessionmaker(bind=engine)
    
session = Session()

"""
    
### 添加数据
    
# 向表中添加单条数据
    
session.add(Group("dba"))
    
session.add(Group("ddd"))

# 向表中添加多条数据
    
session.add_all(
    
    [
    
        User(username="a", group_id=1),
    
        User(username="b", group_id=2),
    
        User(username="c", group_id=1)
    
    ]
    
)

session.commit()
    
"""

# # 查询单表中所有数据
    
# ret = session.query(User).all()
    
# print(ret)  # 输出User类中__repr__方法中返回的字符串
    
# for obj in ret:
    
#     print(obj.nid, obj.username, obj.group_id)
    
#
    
# # 通过指定列查询
    
# ret = session.query(User.nid, User.username).all()
    
# print(ret)  # 返回一个列表,列表中包含每一行的数据  [(2, 'a'), (3, 'b'), (4, 'c')]

# # 根据指定条件查询
    
# ret = session.query(User).filter(User.username == "a").all()
    
# obj = ret[0]
    
# print(obj.nid, obj.username, obj.group_id)

# 连表查询

# 通过join进行连表查询
    
# ret = session.query(User).join(Group)   # 返回执行的sql语句
    
# print(ret)
    
# print("------")
    
# ret = session.query(User).join(Group).all()
    
# for obj in ret:
    
#     print(obj.nid, obj.username, obj.group_id)
    
#
    
# ret = session.query(User, Group).join(Group).all()
    
# print(ret)
    
#
    
#
    
# ret = session.query(User.username, Group.caption).join(Group).all()
    
# print(ret)

# 通过relationship在创建表的类中指定连表的对应关系,然后进行连表查询
    
# 正向查询  (正向查找不能够过滤组的字段)
    
ret = session.query(User).all()
    
for obj in ret:
    
    # obj代指user表中的每一行数据
    
    # obj.group代指obj当前对应的group表中数据的对象
    
    print(obj.nid, obj.username, obj.group_id, obj.group, obj.group.nid, obj.group.caption)

# 反向查询
    
# 查找所有组名为dba的用户信息
    
obj = session.query(Group).filter(Group.caption=="dba").first()
    
print(obj.nid, obj.caption, obj.user)    # obj.user 这个地方的user是在User类中使用relationship创建对应关系中 backref对应的值

  • 多对多

    • 原始方法和新式方法1
    ### 关系在第三张表中

from sqlalchemy import create_engine
    
from sqlalchemy.ext.declarative import declarative_base
    
from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index
    
from sqlalchemy.orm import sessionmaker, relationship

engine = create_engine("mysql+pymysql://tuocigaoshou:Eb^BEF38E9FBC36CA775@111.204.117.99:3306/test", max_overflow=5)

Base = declarative_base()

class Host(Base):
    
    """
    
    主机表
    
    """
    
    __tablename__ = "host"
    
    nid = Column(Integer, primary_key=True, autoincrement=True)
    
    hostname = Column(String(32))
    
    port = Column(String(32))
    
    ip = Column(String(32))

class HostUser(Base):
    
    """
    
    登录主机的用户表
    
    """
    
    __tablename__ = "host_user"
    
    nid = Column(Integer, primary_key=True, autoincrement=True)
    
    username = Column(String(32))

class Host_HostUser(Base):
    
    """
    
    关系表
    
    """
    
    __tablename__ = "host_to_host_user"
    
    nid = Column(Integer, primary_key=True, autoincrement=True)
    
    host_id = Column(Integer, ForeignKey("host.nid"))
    
    host_user_id = Column(Integer, ForeignKey("host_user.nid"))

    host = relationship("Host", backref="h")
    
    host_user = relationship("HostUser", backref="u")

# Base.metadata.create_all(engine)    # 创建表

Session = sessionmaker(bind=engine)
    
session = Session()

# # 向host主机表中添加多条数据
    
# session.add_all(
    
#     [
    
#         Host(hostname="c1", port="22", ip="1.1.1.1"),
    
#         Host(hostname="c2", port="22", ip="1.1.1.2"),
    
#         Host(hostname="c3", port="22", ip="1.1.1.3"),
    
#     ]
    
# )

# # 向host_user登录主机用户表中添加多条数据
    
# session.add_all(
    
#     [
    
#         HostUser(username="root"),
    
#         HostUser(username="aa"),
    
#         HostUser(username="bb"),
    
#         HostUser(username="cc"),
    
#     ]
    
# )

# # 向host_to_host_user关系表中添加多条数据
    
# session.add_all(
    
#     [
    
#         Host_HostUser(host_id=1, host_user_id=1),
    
#         Host_HostUser(host_id=1, host_user_id=2),
    
#         Host_HostUser(host_id=1, host_user_id=3),
    
#         Host_HostUser(host_id=1, host_user_id=4),
    
#         Host_HostUser(host_id=2, host_user_id=2),
    
#         Host_HostUser(host_id=2, host_user_id=4),
    
#         Host_HostUser(host_id=3, host_user_id=1),
    
#         Host_HostUser(host_id=3, host_user_id=3),
    
#     ]
    
# )

# session.commit()

# 需求:找出能够登录主机名为c1的所有用户
    
# ### 原始方式
    
# # 从host表中将找到主机名为c1的nid
    
# host_obj = session.query(Host).filter(Host.hostname == "c1").first()
    
#
    
# # 通过主机名为c1的nid在关系表中找到用户的id
    
# host_2_host_user = session.query(Host_HostUser.host_user_id).filter(Host_HostUser.host_id==host_obj.nid).all()
    
#
    
# r = zip(*host_2_host_user)
    
# users = session.query(HostUser.username).filter(HostUser.nid.in_(list(r)[0])).all()
    
# print(users)

### 原始方式结合
    
ret = session.query(HostUser.username).filter(HostUser.nid.in_(session.query(Host_HostUser.host_user_id).filter(Host_HostUser.host_id == session.query(Host.nid).filter(Host.hostname == 'c1')))).all()
    
print(ret)

### 新式方法
    
# 通过在Host_HostUser类中使用relationship建立与Host类和HostUser类建立关系,然后使用反向查询和正向询进行查找
    
host_obj = session.query(Host).filter(Host.hostname=="c1").first()
    
for item in host_obj.h:   # host_obj.h 反向查询
    
    print(item.host_user.username)  # item.host_user.username  正向查询
    • 新式方法2
    ### 关系在第1张表中 secondary=Host_HostUser.__table__ 要将关系表放在最上面 如果不使用lambda则应该将关系表放在最上面

from sqlalchemy import create_engine
    
from sqlalchemy.ext.declarative import declarative_base
    
from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index
    
from sqlalchemy.orm import sessionmaker, relationship

engine = create_engine("mysql+pymysql://tuocigaoshou:Eb^BEF38E9FBC36CA775@111.204.117.99:3306/test", max_overflow=5)

Base = declarative_base()

class Host_HostUser(Base):
    
    """
    
    关系表
    
    """
    
    __tablename__ = "host_to_host_user"
    
    nid = Column(Integer, primary_key=True, autoincrement=True)
    
    host_id = Column(Integer, ForeignKey("host.nid"))
    
    host_user_id = Column(Integer, ForeignKey("host_user.nid"))

class Host(Base):
    
    """
    
    主机表
    
    """
    
    __tablename__ = "host"
    
    nid = Column(Integer, primary_key=True, autoincrement=True)
    
    hostname = Column(String(32))
    
    port = Column(String(32))
    
    ip = Column(String(32))

    host_user = relationship("HostUser",
    
                             secondary=Host_HostUser.__table__,
    
                             backref="h")

class HostUser(Base):
    
    """
    
    登录主机的用户表
    
    """
    
    __tablename__ = "host_user"
    
    nid = Column(Integer, primary_key=True, autoincrement=True)
    
    username = Column(String(32))

# Base.metadata.create_all(engine)    # 创建表

Session = sessionmaker(bind=engine)
    
session = Session()

# # 向host主机表中添加多条数据
    
# session.add_all(
    
#     [
    
#         Host(hostname="c1", port="22", ip="1.1.1.1"),
    
#         Host(hostname="c2", port="22", ip="1.1.1.2"),
    
#         Host(hostname="c3", port="22", ip="1.1.1.3"),
    
#     ]
    
# )

# # 向host_user登录主机用户表中添加多条数据
    
# session.add_all(
    
#     [
    
#         HostUser(username="root"),
    
#         HostUser(username="aa"),
    
#         HostUser(username="bb"),
    
#         HostUser(username="cc"),
    
#     ]
    
# )

# # 向host_to_host_user关系表中添加多条数据
    
# session.add_all(
    
#     [
    
#         Host_HostUser(host_id=1, host_user_id=1),
    
#         Host_HostUser(host_id=1, host_user_id=2),
    
#         Host_HostUser(host_id=1, host_user_id=3),
    
#         Host_HostUser(host_id=1, host_user_id=4),
    
#         Host_HostUser(host_id=2, host_user_id=2),
    
#         Host_HostUser(host_id=2, host_user_id=4),
    
#         Host_HostUser(host_id=3, host_user_id=1),
    
#         Host_HostUser(host_id=3, host_user_id=3),
    
#     ]
    
# )

# session.commit()

# 需求:找出能够登录主机名为c1的所有用户
    
### 新式方法二

host_obj = session.query(Host).filter(Host.hostname=="c1").first()
    
print(host_obj.host_user)
    • 新式方法三
    ### secondary="host_to_host_user" 关系表无顺序要求 如果不使用lambda则应该将关系表放在最上面

from sqlalchemy import create_engine
    
from sqlalchemy.ext.declarative import declarative_base
    
from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index
    
from sqlalchemy.orm import sessionmaker, relationship

engine = create_engine("mysql+pymysql://tuocigaoshou:Eb^BEF38E9FBC36CA775@111.204.117.99:3306/test", max_overflow=5)

Base = declarative_base()

class Host(Base):
    
    """
    
    主机表
    
    """
    
    __tablename__ = "host"
    
    nid = Column(Integer, primary_key=True, autoincrement=True)
    
    hostname = Column(String(32))
    
    port = Column(String(32))
    
    ip = Column(String(32))

    host_user = relationship("HostUser",
    
                             secondary="host_to_host_user",
    
                             backref="h")

class HostUser(Base):
    
    """
    
    登录主机的用户表
    
    """
    
    __tablename__ = "host_user"
    
    nid = Column(Integer, primary_key=True, autoincrement=True)
    
    username = Column(String(32))

class Host_HostUser(Base):
    
    """
    
    关系表
    
    """
    
    __tablename__ = "host_to_host_user"
    
    nid = Column(Integer, primary_key=True, autoincrement=True)
    
    host_id = Column(Integer, ForeignKey("host.nid"))
    
    host_user_id = Column(Integer, ForeignKey("host_user.nid"))

# Base.metadata.create_all(engine)    # 创建表

Session = sessionmaker(bind=engine)
    
session = Session()

### 新式方法三

host_obj = session.query(Host).filter(Host.hostname=="c1").first()
    
print(host_obj.host_user)
    • 新式方法四
    ### secondary=lambda : Host_HostUser.__table__  如果不使用lambda则应该将关系表放在最上面

from sqlalchemy import create_engine
    
from sqlalchemy.ext.declarative import declarative_base
    
from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index
    
from sqlalchemy.orm import sessionmaker, relationship

engine = create_engine("mysql+pymysql://tuocigaoshou:Eb^BEF38E9FBC36CA775@111.204.117.99:3306/test", max_overflow=5)

Base = declarative_base()

class Host(Base):
    
    """
    
    主机表
    
    """
    
    __tablename__ = "host"
    
    nid = Column(Integer, primary_key=True, autoincrement=True)
    
    hostname = Column(String(32))
    
    port = Column(String(32))
    
    ip = Column(String(32))

    host_user = relationship("HostUser",
    
                             secondary=lambda : Host_HostUser.__table__,
    
                             backref="h")

class HostUser(Base):
    
    """
    
    登录主机的用户表
    
    """
    
    __tablename__ = "host_user"
    
    nid = Column(Integer, primary_key=True, autoincrement=True)
    
    username = Column(String(32))

class Host_HostUser(Base):
    
    """
    
    关系表
    
    """
    
    __tablename__ = "host_to_host_user"
    
    nid = Column(Integer, primary_key=True, autoincrement=True)
    
    host_id = Column(Integer, ForeignKey("host.nid"))
    
    host_user_id = Column(Integer, ForeignKey("host_user.nid"))

# Base.metadata.create_all(engine)    # 创建表

Session = sessionmaker(bind=engine)
    
session = Session()

### 新式方法四

host_obj = session.query(Host).filter(Host.hostname=="c1").first()
    
print(host_obj.host_user)
    • 新式方法五
    ### 关系表需要使用Table()进行创建
    
### relationship 中secondary=Host_HostUser, 如果不使用lambda则应该将关系表放在最上面

from sqlalchemy import create_engine
    
from sqlalchemy.ext.declarative import declarative_base
    
from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index, Table
    
from sqlalchemy.orm import sessionmaker, relationship

engine = create_engine("mysql+pymysql://tuocigaoshou:Eb^BEF38E9FBC36CA775@111.204.117.99:3306/test", max_overflow=5)

Base = declarative_base()

Host_HostUser = Table('host_to_host_user', Base.metadata,
    
              Column('nid', Integer, primary_key=True, autoincrement=True),
    
              Column('host_id', Integer, ForeignKey("host.nid")),
    
              Column('host_user_id', Integer, ForeignKey("host_user.nid")),
    
)

class Host(Base):
    
    """
    
    主机表
    
    """
    
    __tablename__ = "host"
    
    nid = Column(Integer, primary_key=True, autoincrement=True)
    
    hostname = Column(String(32))
    
    port = Column(String(32))
    
    ip = Column(String(32))

    host_user = relationship("HostUser",
    
                             secondary=Host_HostUser,
    
                             backref="h")

class HostUser(Base):
    
    """
    
    登录主机的用户表
    
    """
    
    __tablename__ = "host_user"
    
    nid = Column(Integer, primary_key=True, autoincrement=True)
    
    username = Column(String(32))

# Base.metadata.create_all(engine)    # 创建表

Session = sessionmaker(bind=engine)
    
session = Session()

### 新式方法五

host_obj = session.query(Host).filter(Host.hostname=="c1").first()
    
print(host_obj.host_user)

paramiko模块

python学习之路-13的更多相关文章

  1. Python学习之路13☞常用模块

    一 time模块 在Python中,通常有这几种方式来表示时间: 时间戳(timestamp):通常来说,时间戳表示的是从1970年1月1日00:00:00开始按秒计算的偏移量.我们运行“type(t ...

  2. python学习之路-day2-pyth基础2

    一.        模块初识 Python的强大之处在于他有非常丰富和强大的标准库和第三方库,第三方库存放位置:site-packages sys模块简介 导入模块 import sys 3 sys模 ...

  3. Python学习之路-Day2-Python基础2

    Python学习之路第二天 学习内容: 1.模块初识 2.pyc是什么 3.python数据类型 4.数据运算 5.bytes/str之别 6.列表 7.元组 8.字典 9.字符串常用操作 1.模块初 ...

  4. Python学习之路【第一篇】-Python简介和基础入门

    1.Python简介 1.1 Python是什么 相信混迹IT界的很多朋友都知道,Python是近年来最火的一个热点,没有之一.从性质上来讲它和我们熟知的C.java.php等没有什么本质的区别,也是 ...

  5. python学习之路------你想要的都在这里了

    python学习之路------你想要的都在这里了 (根据自己的学习进度后期不断更新哟!!!) 一.python基础 1.python基础--python基本知识.七大数据类型等 2.python基础 ...

  6. Python学习之路-Day2-Python基础3

    Python学习之路第三天 学习内容: 1.文件操作 2.字符转编码操作 3.函数介绍 4.递归 5.函数式编程 1.文件操作 打印到屏幕 最简单的输出方法是用print语句,你可以给它传递零个或多个 ...

  7. Python学习之路-Day1-Python基础

    学习python的过程: 在茫茫的编程语言中我选择了python,因为感觉python很强大,能用到很多领域.我自己也学过一些编程语言,比如:C,java,php,html,css等.但是我感觉自己都 ...

  8. python学习之路网络编程篇（第四篇）

    python学习之路网络编程篇(第四篇) 内容待补充

  9. python 学习之路开始了

    python 学习之路开始了.....记录点点滴滴....

随机推荐

  1. Javascript:重用之道

    近期写了大量的js,愈发觉得自己的代码过于冗余,所以,利用周末的时间研习代码重用之道,有了这篇博文所得: 重用代码: 1.尽量保证 HTML 代码结构一致,可以通过父级选取子元素 2.把核心主程序实现 ...

  2. PhoneGap 和 PhoneGap Build 是什么?

    PhoneGap是目前唯一支持7种平台的开源移动开发框架,支持的平台包括iOS.Android.BlackBerry OS.Palm WebOS.Windows Phone 7.Symbian和Bad ...

  3. [RxJS] Resubscribing to a Stream with Repeat

    When you complete a stream, there’s no way to restart it, you must resubscribe. This lesson shows ho ...

  4. 在Ubuntu上下载、编译和安装Android最新内核源代码（Linux Kernel）

    文章转载至CSDN社区罗升阳的安卓之旅,原文地址:http://blog.csdn.net/luoshengyang/article/details/6564592 在前一篇文章提到,从源代码树下载下 ...

  5. HDU 3265 Posters（线段树）

    HDU 3265 Posters pid=3265" target="_blank" style="">题目链接 题意:给定一些矩形海报.中间有 ...

  6. web请求的处理流程

    web请求的处理流程如下: 1.客户发起请求到服务器网卡:2.服务器网卡接受到请求后转交给内核处理:3.内核根据请求对应的套接字,将请求交给工作在用户空间的Web服务器进程4.Web服务器进程根据用户 ...

  7. CSS 定位元素之 relative

    1. relative 和 absolute relative 会限制 absolute. absolute 会根据 父级的的定位元素来定位. 2. overflow 和 absolue 当overf ...

  8. javascript-Blob文件对象

    一个Blob对象就是一个包含有只读原始数据的类文件对象.Blob对象中的数据并不一定得是JavaScript中的原生形式.File接口基于Blob,继承了Blob的功能,并且扩展支持了用户计算机上的本 ...

  9. View not attached to window manager

    java.lang.IllegalArgumentException: View not attached to window manager 在用ProgressDialog的时候,任务结束后Dis ...

  10. linux for循环

    一定要记得写后面的分号:http://www.runoob.com/linux/linux-shell-variable.html 这个页面的课程的循环教程是有问题的 for color in yel ...