在Python的Flask框架下使用sqlalchemy库的简单教程

  <span style="font-size:18px;">from flask import Flask 
  from flask.ext.sqlalchemy import SQLAlchemy</span>

  <span style="font-size:18px;">mysqlname='<span style="color: rgb(230, 219, 116); font-family: 'Source Code Pro'; font-size: 13pt; background-color: rgb(39, 40, 34);">mysql://user:passwd@127.0.0.1/student?charset=utf8</span>'</span> 

  <span style="font-size:18px;">app = Flask(__name__) 
  app.config['SQLALCHEMY_DATABASE_URI'] = mysqlname 
  db = SQLAlchemy(app)</span> 

  <span style="font-size:18px;">class User(db.Model): 
   
    """存储 每种报警类型的数量 ， 以 分钟 为单位进行统计 
    :param source: string ,报警来源 
    :param network_logic_area: string ,该报警所属的逻辑网络区域 
    :param start_time: datetime , 报警发生时间 
    """ 
   
    __tablename__ = 'hello' 
    id = db.Column(db.Integer , primary_key = True) 
    source = db.Column(db.String(255) ) 
    network_logic_area = db.Column(db.String(255) ) 
    start_time = db.Column(db.DateTime) 
    count = db.Column(db.Integer) 
   
    def __init__(self , source , network_logic_area , start_time , count): 
      self.source = source 
      self.network_logic_area = network_logic_area 
      self.start_time = start_time 
      self.count = count 
   
    def alter(self): 
      self.count += 1;</span> 

  <span style="font-size:18px;">    p = User(........) 
      db.session.add(p) 
      db.session.commit()</span> 

User.query.get(1)

<User
 u'admin'>

peter
=

User.query.filter_by(username='peter').first() 
#注意：精确查询函数query.filter_by()，是通过传递参数进行查询；其他增强型查询函数是query.filter()，通过传递表达式进行查询。

print(peter.id) 
#如果数据不存在则返回None

User.query.filter(User.email.endswith('@example.com')).all()

[<User
 u'admin'>,
 <User u'guest'>]

peter
=

User.query.filter(User.username
 !=

'peter').first()

print(peter.id)

from

sqlalchemy import

not_

peter
=

User.query.filter(not_(User.username=='peter')).first()

print(peter.id)

from

sqlalchemy import

and_

peter
=

User.query.filter(and_(User.username=='peter',
 User.email.endswith('@example.com'))).first()

print(peter.id)

from

sqlalchemy import

or_

peter
=

User.query.filter(or_(User.username
 !=

'peter',
 User.email.endswith('@example.com'))).first()

print(peter.id)

  <span style="font-size:18px;">insert_table.db.engine.execute(' ..... ')</span> 

  <span style="font-size:18px;">me = User(........)</span> 

  <span style="font-size:18px;">db.session.delete(me) 
  db.session.commit()</span> 

Code example:
 
u
=

User.query.first()

u.username
=

'guest' 
#更新数据和变量赋值那么简单，但必须是通过查询返回的对象。

db.session.commit()