import sqlite3

conn = sqlite3.connect(‘db.sqlite3‘)

#获取游标对象
cur = conn.cursor()

#执行一系列SQL语句
#建立一张表
#cur.execute("create table demo(num int, str vachar(20));")
#插入一些记录
cur.execute("insert into demo values(%d, ‘%s‘)" % (1, ‘aaa‘))
cur.execute("insert into demo values(%d, ‘%s‘)" % (2, ‘bbb‘))

#更新一条记录
cur.execute("update demo set str=‘%s‘ where num =%d" % (‘ddd‘,3))

#查询
cur.execute("select * from demo;")
rows = cur.fetchall()
print("number of records:", len(rows))

for i in rows:
    print(i)
    
#提交事务
conn.commit()

#关闭游标对象
cur.close()

#关闭数据库连接
conn.close()

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String

Base = declarative_base()   #定义一个实例，所有表必须继承该实例

class Account(Base):
    __tablename__ = ‘account‘   #表名
    
    #字段名
    id = Column(Integer, primary_key=True)
    user_name = Column(String(50), nullable=False)
    password = Column(String(200), nullable=False)
    title = Column(String(50))
    salary = Column(Integer)
    
    def is_active(self):
        #假设所有用户都是活跃用户
        return True
    
    def get_id(self):
        #返回帐户id,该方法返回属性值提高了表的封装性
        return self.id
        
    def is_authenticated(self):
        #假设已通过验证
        return True
        
    def is_anonymous(self):
        #具有登录名和密码的帐户不是匿名用户
        return False

from sqlalchemy import create_engine
from sqlalchemy.orm import scoped_session, sessionmaker
#定义连接数据库用到的数据库字符串
db_connect_string = ‘mysql://root:123456@localhost:3306/sqlalchemy_db?charset=utf8‘
#如果数据库开启了ssl连接，定义ssl字符串
ssl_args = {
    ‘ssl‘:{
        ‘cert‘: ‘/home/ssl/client-cert.pem‘,
        ‘key‘: ‘/home/shouse/ssl/client-key.pem‘,
        ‘ca‘: ‘/home/shouse/ssl/ca-cert.pem‘
        }
    }
#如果数据库开启了ssl连接，需要传入ssl    
engine = create_engine(db_connect_string, connect_args=ssl_args)
#定义会话类型
SessionType = scoped_session(sessionmaker(bind=engine, expire_on_commit=False))

def GetSession():
    #创建SessionType的实例，用于数据库操作
    return SessionType()

from contextlib import contextmanager

#定义上下文函数，使能够自动进行事务处理，
#定义上下文件函数的方法就是加上contextmanager装饰器
#执行逻辑：在函数开始时建立数据库会话，此时会自动建立一个数据库事务；当发生异常时回滚（rollback）事务，当
#退出时关闭(close)连接
@contextmanager
def session_scope():
    session = GetSession()
    
    try:
        yield session
        session.commit()
    except:
        session.rollback()
        raise
    finally:
        session.close()

import orm
from sqlalchemy import or_

def InsertAccount(user, password, title, salary):
    with session_scope() as session:     #新增操作
        account = orm.Account(user_name=user, password=password, title=title, salary=salary)
        session.add(account)
def CetAccount(id=None, user_name=None):       #查询操作，查询结果是一个对象集合，同样可以用all()获取所有数据
    with session_scope() as session:
        return session.query(orm.Account).filter(
            or_(orm.Account.id==id, orm.Account.user_name==user_name)
        ).first()
        
def DeleteAccount(user_name):       #删除操作
    with session_scope() as session:
        account = GetAccount(user_name=user_name)
        if account:
            session.delete(account)

def UpdateAccount(id, user_name, password, title, salary):     #更新操作
    with session_scope() as session:
        account = session.query(orm.Account).filter(orm.Account.id=id).first()
        if not account: return
        account.user_name = user_name
        account.password = password
        account.title = title
        account.salary = salary
        
#调用新增操作
InsertAccount(‘David Li‘, "123", "System Manager", 3000)
InsertAccount(‘Rebeca Li‘, ‘‘, ‘Accountant‘, 3000)

#查询操作
GetAccount(2)

#删除操作
DeleteAccount(‘David Li‘)

#更新操作
UpdateAccount(1, "David Li", "none", "System Manager", 2000)

session.query(Account).filter(Account.user_name==‘Jack‘)
session.query(Account).filter(Account.salary==2000)

session.query(Account).filter(Account.user_name != ‘Jack‘)

session.query(Account).filter(Account.salary != 2000)

session.query(Account).filter(Account.salary > 3000)

#查询所有名字中包含字母i的用户
session.query(Account).filter(Account.user_name.like(‘%i%‘))

#查询所有title中以Manager结尾的用户
session.query(Account).filter(Account.title.like(‘%Manager‘))

#查询的有名字中以Da开头的用户
session.query(Account).filter(Account.user_name.like(‘Da%‘))

#查询id不为1，3，5的记录
session.query(Account).filter(~Account.id.in_([1,3,5]))

#查询工资不为2000，3000，4000的记录
session.query(Account).filter(~Account.salary.in_([2000,3000,4000]))

#查询所有title不为Engineer和Accountant的记录
session.query(Account).filter(~Account.title.in_([‘Account‘,‘Engineer‘]))

#查询salary为空值的记录
session.query(Account).filter(Account.salary.is_(None))
session.query(Account).filter(Account.salary == None)

#查询salary不为空值的记录
session.query(Account).filter(Account.salary.isnot(None))
session.query(Account).filter(Account.salary != None)

#查询id不为1，3，5的记录
session.query(Account).filter(~Account.id.in_([1,3,5]))

#直接多个条件查询
session.query(Account).filter(Account.title=‘Engineer‘, Account.salary==3000)
#用关键字and_进行与逻辑查询
from sqlalchemy import and_
session.query(Account).filter(and_(Account.title==‘Engineer‘, Account.salary==3000))
#通过多个filter链接查询
session.query(Account).filter(Account.title==‘Engineer‘).filter(Account.salary==3000)

from sqlalchemy import or_

#查询title是Engineer或者salary为3000的记录
session.query(Account).filter(or_(Account.title==‘Engineer‘, Account.salary==3000))