5.5.使用更通用的sqlalchemy操作数据库

# 导入:
from sqlalchemy import Column, String, create_engine
from sqlalchemy.orm import sessionmaker
from sqlalchemy.ext.declarative import declarative_base

#sqlalchemy依赖于mysqldb，而mysqldb被改为pymysql
#因此要将pymysql声明为mysqldb
import pymysql
pymysql.install_as_MySQLdb()

# 创建对象的基类:
Base = declarative_base()

# 定义User对象:
class Angle2(Base):
    # 表的名字:
    __tablename__ = 'angle2'

    # 表的结构:
    id = Column(String(20), primary_key=True)
    name = Column(String(20))

# 初始化数据库连接:
engine = create_engine('mysql://root:@localhost:3306/Angle', echo = True)

一、创建表：

Base.metadata.create_all(engine)

二、查看是否创建成果：

engine.table_names()

三、初始化一个session对象：

from sqlalchemy.orm import sessionmaker

Session = sessionmaker(bind=engine)

session = Session()

通过session对象，可以对数据库进行操作。
四、添加、更新对象

user_1 = User(id=1, name='wang', password='123') 

session.add(user_1)

user_2 = User(id=2, name='qian', password='234')                                                                                                                                         

user_3 = User(id=3, name='sun', password='345')

session.add_all([user_2, user_3])

session.commit()

session.dirty:查看删除对象
session.dirty:查看新增对象
session.rollback():回滚

五、查询

session.query(User).filter_by(name='wang').first()

session.query(User).filter_by(name='wang').all()

for name in session.query(User.name).filter_by(password='123'):
    print(name)

for user in session.query(User).order_by(User.id)[1:3]:
    print(user.name)

六、查询时的通用过滤符号：

# equal
query.filter(User.name == 'ed')

# not equal
query.filter(User.name != 'ed')

# like 
query.filter(User.name.like('%ed%'))

# in
query.filter(User.name.in_(['ed', 'wendy', 'jack']))

# not in
query.filter(~User.name.in_(['ed', 'wendy', 'jack']))

# add

# use and_()
from sqlalchemy import and_
query.filter(and_(User.name == 'ed', User.fullname == 'Ed Jones'))

# or send multiple expressions to .filter()
query.filter(User.name == 'ed', User.fullname == 'Ed Jones')

# or chain multiple filter()/filter_by() calls
query.filter(User.name == 'ed').filter(User.fullname == 'Ed Jones')

# or --Make sure you use or_() and not the Python or operator!
from sqlalchemy import or_
query.filter(or_(User.name == 'ed', User.name == 'wendy'))

# match
query.filter(User.name.match('wendy'))

参考链接：http://www.cnblogs.com/wswang/p/5826347.html
https://linux-wang.gitbooks.io/sqlalchemy-docs-cn/content/SQLAlchemyORM/Object-Relational-Tutorial.html