python入门练习之如何连接数据库

!/usr/bin/python

-- coding: UTF-8 --

author = 'luke'

from sqlalchemy import create_engine

from sqlalchemy.ext.declarative import declarative_base

from sqlalchemy import Column, Integer, String

from sqlalchemy.orm import sessionmaker

import traceback

打开数据库连接

session_class = sessionmaker(bind=connect) # 创建与数据库的会话session class ,这里返回给session的是个class,不是实例

Base = declarative_base() # 生成ORM基类

##################User Class##################################

class User(Base):

tablename = "hello_word" # 表名

id = Column(String(255), primary_key=True)

score = Column(Integer)

sccess_times = Column(Integer)

fail_times = Column(Integer)

http_type = Column(String(255))

##################IpRate Class##################################

class IpRate(Base):

tablename = "ip_rate" # 表名

id = Column(String(255), primary_key=True)

fail_times = Column(Integer)

score = Column(Integer)

sccess_times = Column(Integer)

http_type = Column(String(255))

def _addOne(obj):

try:

    session = session_class()
    #新增一条数据
    #原生sql：insert  into mysql.hello_word(name,password) values("test2","1234")；
    #obj = User(id="127.0.0.1:8080", score=5,sccess_times=0,fail_times=0,http_type='http')  #生成你要创建的数据对象
    session.add(obj) #把要创建的数据对象添加到这个session里， 一会统一创建
    session.commit() #统一提交，创建数据，在此之前数据库是不会有新增数据的
    print('addOne ok...')
except:
    session.rollback()
    print ("Error: unable to addOne data")
finally:
    session.close()

def _addAll(objlist):

'''

objlist: object list

'''

try:

session = session_class()

session.add_all(objlist) #把要创建的数据对象添加到这个session里， 一会统一创建

session.commit() #统一提交，创建数据，在此之前数据库是不会有新增数据的

except:

session.rollback()

print ("Error: unable to addAll data")

finally:

session.close()

def _del(obj):

'''

objlist: object list

'''

try:

session = session_class()

session.query(obj).delete() #通过session查询User类，然后过滤出id>5的进行删除

print ("_del...ok")

session.commit()

except:

session.rollback()

print ("Error: unable to delete data")

finally:

session.close()

def _updateOneById(obj,id,key,value):

try:

session = session_class()

data = session.query(obj).filter(id==id)

setattr(object=data,name=key,value=value)

session.commit()

print ("_updateOneById...ok")

except:

session.rollback()

print ("Error: unable to update data")

finally:

session.close()

def _fetchOneById(obj,id):

try:

session = session_class()

results = session.query(obj).filter(obj.idid)

if(len(results) > 0):

print ("_fetchOneById...ok")

return results[0]

else:

return None

except:

print ("Error: unable to _fetchOneById data")

finally:

session.close()

def _fetchAll(obj):

try:

session = session_class()

results = session.query(obj).all() #查询所有

if(len(results) > 0):

print ("_fetchAll...ok")

return results

else:

return None

except:

print ("Error: unable to _fetchAll data")

finally:

session.close()

if name'main':

try:

#Base.metadata.create_all(connect) # 创建表结构

#print('创建成功')

user = User(id='127.0.0.2:8080',score=10,sccess_times=0,fail_times=0,http_type='http')

# user.id = '127.0.0.1:8080'

# user.score = 10

# user.sccess_times = 0

# user.fail_times = 0

# user.http_type = 'http'

#_addOne(user)

data = _fetchOneById(User,'127.0.0.1:8080')

print(data)

data2 = _fetchAll(User)

_updateOneById(User,'127.0.0.1:8080','score',1)

_del(user)

except BaseException as e:

traceback.print_exc()