SQLAchemy

SQLAchemy是Python编程语言下的一款ORM框架，该框架建立在数据库API之上，使用关系对象映射进行数据库操作，简言之便是：将对象转换成SQL，然后使用数据库PAI执行SQL并获取执行结果。

SQLAchemy本身无法操作数据库，必须以第三方插件，Dialect用于和数据库PAI进行交流，根据配置文件的不同调用不同的数据库API，从而实现对数据库的操作。

MySQL-Python

    mysql+mysqldb://<user>:<password>@<host>[:<port>]/<dbname>

  

pymysql

    mysql+pymysql://<username>:<password>@<host>/<dbname>[?<options>]

  

MySQL-Connector

    mysql+mysqlconnector://<user>:<password>@<host>[:<port>]/<dbname>

  

cx_Oracle

    oracle+cx_oracle://user:pass@host:port/dbname[?key=value&key=value...]

  

更多详见：http://docs.sqlalchemy.org/en/latest/dialects/index.html

一、底层处理
使用Engine/ConnectionPoolling/Dialect进行数据库操作，Engine使用ConnectionPooling连接数据库，然后再通过Dialect执行SQL语句。

from sqlalchemy import create_engine

engine = create_engine("mysql+pymysql://test:123456@192.168.254.129/test", max_overflow=5)
# 执行sql语句
# cur = engine.execute(
#     "insert into sanguo (name,age) values ('zhangzhao',38)"
# )
# # 新插入行自增id
# new_id = cur.lastrowid
# print(new_id)
# cur = engine.execute("select * from sanguo where id > 5")
# 获取一行数据
# ret = cur.fetchone()
# 获取第n行数据
# cur.fetchmany(3)
# 获取所有数据
# cur.fetchall()
# cur = engine.execute("insert into sanguo (name,age) VALUES (%s,%s)",[('lvbu',21),('yuanshao',27)])
# print(ret)

二、ORM功能使用：
使用ORM/Schema TYpe/SQL Expression Language/Engine/ConnectionPooling/Dialect所有组件对数据进行操作。根据类创建对象，对象转换成SQL，执行SQL。

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

engine = create_engine("mysql+pymysql://test:123456@192.168.254.129:3306/test", max_overflow=5)
Base = declarative_base()


class Group(Base):
    __tablename__ = 'groups'
    nid = Column(Integer, primary_key=True, autoincrement=True)
    name = Column(String(32))


class User(Base):
    __tablename__ = 'user'
    nid = Column(Integer, primary_key=True, autoincrement=True)
    name = Column(String(32))
    group_id = Column(Integer, ForeignKey('groups.nid'))

    def __repr__(self):
        """
        自定制
        """
        temp = '%s-%s' %(self.nid, self.name)
        return temp

# 创建数据库函数
def init_db():
    Base.metadata.create_all(engine)

# 删除数据库函数
def drop_db():
    Base.metadata.drop_all(engine)

init_db()

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

engine = create_engine("mysql+pymysql://test:123456@192.168.254.129:3306/test", max_overflow=5)
Base = declarative_base()


class Group(Base):
    __tablename__ = 'groups'
    nid = Column(Integer, primary_key=True, autoincrement=True)
    name = Column(String(32))


class User(Base):
    __tablename__ = 'user'
    nid = Column(Integer, primary_key=True, autoincrement=True)
    name = Column(String(32))
    group_id = Column(Integer, ForeignKey('groups.nid'))

    def __repr__(self):
        """
        自定制
        """
        temp = '%s-%s' %(self.nid, self.name)
        return temp

# 创建数据库函数
def init_db():
    Base.metadata.create_all(engine)

# 删除数据库函数
def drop_db():
    Base.metadata.drop_all(engine)

# init_db()
session = sessionmaker(bind=engine)
sess = session()
# 向组里添加数据
sess.add(Group(name='dba'))
sess.add(Group(name='sa'))
# 批量添加
sess.add_all([User(name='cable', group_id=2),
             User(name='caocao', group_id=1)])
sess.commit()

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

engine = create_engine("mysql+pymysql://test:123456@192.168.254.129:3306/test", max_overflow=5)
Base = declarative_base()


class Group(Base):
    __tablename__ = 'groups'
    nid = Column(Integer, primary_key=True, autoincrement=True)
    name = Column(String(32))


class User(Base):
    __tablename__ = 'user'
    nid = Column(Integer, primary_key=True, autoincrement=True)
    name = Column(String(32))
    group_id = Column(Integer, ForeignKey('groups.nid'))

    def __repr__(self):
        """
        自定制
        """
        temp = '%s-%s' %(self.nid, self.name)
        return temp

# 创建数据库函数
def init_db():
    Base.metadata.create_all(engine)

# 删除数据库函数
def drop_db():
    Base.metadata.drop_all(engine)

# init_db()
session = sessionmaker(bind=engine)
sess = session()
ret = sess.query(User).filter(User.name=='cable').all()
obj = ret[0]    # 默认获取的为对象
print(ret)
print(obj.name)
res = sess.query(User).all()    # 获取所有
print(res)
ret = sess.query(User.name).all()   # 指定获取的字段，即可得到列表
print(ret)

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

engine = create_engine("mysql+pymysql://test:123456@192.168.254.129:3306/test", max_overflow=5)
Base = declarative_base()


class Group(Base):
    __tablename__ = 'groups'
    nid = Column(Integer, primary_key=True, autoincrement=True)
    name = Column(String(32))


class User(Base):
    __tablename__ = 'user'
    nid = Column(Integer, primary_key=True, autoincrement=True)
    name = Column(String(32))
    group_id = Column(Integer, ForeignKey('groups.nid'))

    def __repr__(self):
        """
        自定制
        """
        temp = '%s-%s' %(self.nid, self.name)
        return temp

# 创建数据库函数
def init_db():
    Base.metadata.create_all(engine)

# 删除数据库函数
def drop_db():
    Base.metadata.drop_all(engine)

# init_db()
session = sessionmaker(bind=engine)
sess = session()
# 生成的sql语句
sql = sess.query(User).join(Group)
print(sql)
ret = sess.query(User).join(Group).all()  # 内部自动关联外键
print(ret)
# 左连接left join，默认为inner join
res = sess.query(User).join(Group, isouter=True).all()
print(res)

from sqlalchemy import create_engine,and_,or_,func,Table
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String,ForeignKey,UniqueConstraint,DateTime
from  sqlalchemy.orm import sessionmaker,relationship

Base = declarative_base() #生成一个SqlORM 基类

# 服务器账号和组
# HostUser2Group = Table('hostuser_2_group',Base.metadata,
#     Column('hostuser_id',ForeignKey('host_user.id'),primary_key=True),
#     Column('group_id',ForeignKey('group.id'),primary_key=True),
# )

# 用户和组关系表，用户可以属于多个组，一个组可以有多个人
UserProfile2Group = Table('userprofile_2_group',Base.metadata,
    Column('userprofile_id',ForeignKey('user_profile.id'),primary_key=True),
    Column('group_id',ForeignKey('group.id'),primary_key=True),
)

# 程序登陆用户和服务器账户，一个人可以有多个服务器账号，一个服务器账号可以给多个人用
UserProfile2HostUser= Table('userprofile_2_hostuser',Base.metadata,
    Column('userprofile_id',ForeignKey('user_profile.id'),primary_key=True),
    Column('hostuser_id',ForeignKey('host_user.id'),primary_key=True),
)


class Host(Base):
    __tablename__='host'
    id = Column(Integer,primary_key=True,autoincrement=True)
    hostname = Column(String(64),unique=True,nullable=False)
    ip_addr = Column(String(128),unique=True,nullable=False)
    port = Column(Integer,default=22)
    def __repr__(self):
        return  "<id=%s,hostname=%s, ip_addr=%s>" %(self.id,
                                                    self.hostname,
                                                    self.ip_addr)


class HostUser(Base):
    __tablename__ = 'host_user'
    id = Column(Integer,primary_key=True)
    AuthTypes = [
        (u'ssh-passwd',u'SSH/Password'),
        (u'ssh-key',u'SSH/KEY'),
    ]
    # auth_type = Column(ChoiceType(AuthTypes))
    auth_type = Column(String(64))
    username = Column(String(64),unique=True,nullable=False)
    password = Column(String(255))

    host_id = Column(Integer,ForeignKey('host.id'))
    
    # groups = relationship('Group',
    #                       secondary=HostUser2Group,
    #                       backref='host_list')

    __table_args__ = (UniqueConstraint('host_id','username', name='_host_username_uc'),)

    def __repr__(self):
        return  "<id=%s,name=%s>" %(self.id,self.username)


class Group(Base):
    __tablename__ = 'group'
    id = Column(Integer,primary_key=True)
    name = Column(String(64),unique=True,nullable=False)
    def __repr__(self):
        return  "<id=%s,name=%s>" %(self.id,self.name)


class UserProfile(Base):
    __tablename__ = 'user_profile'
    id = Column(Integer,primary_key=True)
    username = Column(String(64),unique=True,nullable=False)
    password = Column(String(255),nullable=False)
    # host_list = relationship('HostUser',
    #                       secondary=UserProfile2HostUser,
    #                       backref='userprofiles')
    # groups = relationship('Group',
    #                       secondary=UserProfile2Group,
    #                       backref='userprofiles')
    def __repr__(self):
        return  "<id=%s,name=%s>" %(self.id,self.username)


class AuditLog(Base):
    __tablename__ = 'audit_log'
    id = Column(Integer,primary_key=True)
    userprofile_id = Column(Integer,ForeignKey('user_profile.id'))
    hostuser_id = Column(Integer,ForeignKey('host_user.id'))
    action_choices2 = [
        (u'cmd',u'CMD'),
        (u'login',u'Login'),
        (u'logout',u'Logout'),
    ]
    action_type = Column(ChoiceType(action_choices2))
    #action_type = Column(String(64))
    cmd = Column(String(255))
    date = Column(DateTime)

    # user_profile = relationship("UserProfile")
    #bind_host = relationship("BindHost")


engine = create_engine("mysql+pymsql://root:123@localhost:3306/stupid_jumpserver",echo=False)
Base.metadata.create_all(engine) #创建所有表结构

更多请查看：http://www.cnblogs.com/wupeiqi/articles/5699254.html