python 连接操作各类数据库

摘要：

  • 用Python写脚本也有一段时间了，经常操作数据库（MySQL），现在就整理下对各类数据库的操作，如后面有新的参数会补进来，慢慢完善。

一，python 操作 MySQL:详情见：这里

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#!/bin/env python
# -*- encoding: utf-8 -*-
#-------------------------------------------------------------------------------
# Purpose:     example for python_to_mysql
# Author:      zhoujy
# Created:     2013-06-14
# update:      2013-06-14
#-------------------------------------------------------------------------------
import MySQLdb
import os

#建立和数据库系统的连接，格式
#conn   = MySQLdb.connect(host='localhost',user='root',passwd='123456',db='test',port=3306,charset='utf8')

#指定配置文件，确定目录,或则写绝对路径
cwd = os.path.realpath(os.path.dirname(__file__))
db_conf = os.path.join(cwd, 'db.conf')
conn   = MySQLdb.connect(read_default_file=db_conf,host='localhost',db='test',port=3306,charset='utf8')

#要执行的sql语句
query  = 'select id  from t1'

#获取操作游标
cursor = conn.cursor()

#执行SQL
cursor.execute(query)

#获取一条记录,每条记录做为一个元组返回,返回3，游标指到第2条记录。
result1 = cursor.fetchone()
for i in result1:
    print i
#返回影响的行数
    print cursor.rowcount

#获取指定数量记录,每条记录做为一个元组返回,返回1，2，游标从第2条记录开始，游标指到第4条记录。
result2 = cursor.fetchmany(2)
for i in result2:
    for ii in i:
        print ii


#获取所有记录,每条记录做为一个元组返回,返回3，4，7，6,游标从第4条记录开始到最后。
result3 = cursor.fetchall()
for i in result3:
    for ii in i:
        print ii

#获取所有记录,每条记录做为一个元组返回,返回3，4，7，6,游标从第1条记录开始
#重置游标位置，0为偏移量，mode＝absolute | relative,默认为relative
cursor.scroll(0,mode='absolute')
result3 = cursor.fetchall()
for i in result3:
    for ii in i:
        print ii

#以下2种方法都可以把数据插入数据库：
#(one)
for i in range (10,20):
    query2 = 'insert into t1 values("%d",now())' %i
    cursor.execute(query2)
    #提交
    conn.rollback()
#(two)
rows = []
for i in range (10,20):
    rows.append(i)
query2 = 'insert into t1 values("%s",now())'
#executemany 2个参数,第2个参数是变量。
cursor.executemany(query2,rows)
#提交
conn.commit()

#选择数据库
query3 = 'select id from dba_hospital'
#重新选择数据库
conn.select_db('chushihua')

cursor.execute(query3)

result4 = cursor.fetchall()
for i in result4:
    for ii in i:
        print ii
#不定义query，直接执行：
cursor.execute("set session binlog_format='mixed'")

#关闭游标，释放资源
cursor.close()

'''
+------+---------------------+
| id   | modifyT             |
+------+---------------------+
|    3 | 2010-01-01 00:00:00 |
|    1 | 2010-01-01 00:00:00 |
|    2 | 2010-01-01 00:00:00 |
|    3 | 2010-01-01 00:00:00 |
|    4 | 2013-06-04 17:04:54 |
|    7 | 2013-06-04 17:05:36 |
|    6 | 2013-06-04 17:05:17 |
+------+---------------------+

注意：在脚本中，密码写在脚本里面很容易暴露，这样可以用一个配置文件的方式来存密码，如db.conf：

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[client]
user=root
password=123456

二， python 操作 MongoDB:详情见这里

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#!/bin/env python
# -*- encoding: utf-8 -*-
#-------------------------------------------------------------------------------
# Purpose:     example for python_to_mongodb
# Author:      zhoujy
# Created:     2013-06-14
# update:      2013-06-14
#-------------------------------------------------------------------------------
import pymongo
import os

#建立和数据库系统的连接,创建Connection时，指定host及port参数
conn   = pymongo.Connection(host='127.0.0.1',port=27017)

#admin 数据库有帐号，连接-认证-切换库
db_auth = conn.admin
db_auth.authenticate('sa','sa')
#连接数据库
db = conn.abc

#连接表
collection = db.stu

#查看全部表名称
db.collection_names()
#print db.collection_names()

#访问表的数据，指定列
item = collection.find({},{"sname":1,"course":1,"_id":0})
for rows in item:
    print rows.values()

#访问表的一行数据
print collection.find_one()

#得到所有的列
for rows in collection.find_one():
    print rows

#插入
collection.insert({"sno":100,"sname":"jl","course":{"D":80,"S":85}})
#或
u = dict(sno=102,sname='zjjj',course={"D":80,"S":85})
collection.insert(u)

#得到行数
print collection.find().count()
print collection.find({"sno":100})

#排序，按照某一列的值。pymongo.DESCENDING:倒序；pymongo.ASCENDING:升序。按照sno倒序
item = collection.find().sort('sno',pymongo.DESCENDING)
for rows in item:
    print rows.values()

#多列排序
item = collection.find().sort([('sno',pymongo.DESCENDING),('A',pymongo.ASCENDING)])

#更新，第一个参数是条件，第二个参数是更新操作，$set,%inc,$push,$ne,$addToSet,$rename 等
collection.update({"sno":100},{"$set":{"sno":101}})
#更新多行和多列
collection.update({"sno":102},{"$set":{"sno":105,"sname":"SSSS"}},multi=True)

#删除，第一个参数是条件，第二个参数是删除操作。
collection.remove({"sno":101})

'''
sno:学号；sname：姓名；course：科目

db.stu.insert({"sno":1,"sname":"张三","course":{"A":95,"B":90,"C":65,"D":74,"E":100}})
db.stu.insert({"sno":2,"sname":"李四","course":{"A":90,"B":85,"X":75,"Y":64,"Z":95}})
db.stu.insert({"sno":3,"sname":"赵五","course":{"A":70,"B":56,"F":85,"G":84,"H":80}})
db.stu.insert({"sno":4,"sname":"zhoujy","course":{"A":64,"B":60,"C":95,"T":94,"Y":85}})
db.stu.insert({"sno":5,"sname":"abc","course":{"A":87,"B":70,"Z":56,"G":54,"H":75}})
db.stu.insert({"sno":6,"sname":"杨六","course":{"A":65,"U":80,"C":78,"R":75,"N":90}})
db.stu.insert({"sno":7,"sname":"陈二","course":{"A":95,"M":68,"N":84,"S":79,"K":89}})
db.stu.insert({"sno":8,"sname":"zhoujj","course":{"P":90,"B":77,"J":85,"K":68,"L":80}})
db.stu.insert({"sno":9,"sname":"ccc","course":{"Q":85,"B":86,"C":90,"V":87,"U":85}})

'''

计算Mongodb文档中各集合的数目：

import pymongo

conn   = pymongo.Connection(host='127.0.0.1',port=27017)
db = conn.abc    #abc文档
for tb_name in db.collection_names():     #循环出各集合名
    Count = db[tb_name].count()            #计算各集合的数量
    if Count > 2:                                 #过滤条件
        print tb_name + ':' + str(Count)

'''
conn   = pymongo.Connection(host='127.0.0.1',port=27017)
db = conn.abc
for tb_name in db.collection_names():
    print tb_name + ':'
    exec('print ' + 'db.'+tb_name+'.count()')      #变量当集合的处理方式

OR

conn   = pymongo.Connection(host='127.0.0.1',port=27017)
db = conn.abc
for tb_name in db.collection_names():
    mon_dic=db.command("collStats", tb_name)      #以字典形式返回
    print mon_dic.get('ns'),mon_dic.get('count')

'''

Note: MongoDB升级到了3.0之后，用python的连接会出错：

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pymongo.errors.OperationFailure: command SON([('authenticate', 1), ('user', u'dba'), ('nonce', u'8c7842b068e14d3'), ('key', u'584ec63f1cdfd8525ce33d99cd269c2c')]) failed: auth failed
表示认证失败，说明MongoDB升级之后，对用用户的加密方式改变了。那就升级pymongo。
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$ sudo pip install pymongo --upgrade
升级成功，要是没有安装pip，看这里：http://www.saltycrane.com/blog/2010/02/how-install-pip-ubuntu/

ubuntu10.10之后：

$ sudo apt-get install python-pip python-dev build-essential
$ sudo pip install --upgrade pip
$ sudo pip install --upgrade virtualenv
ubuntu10.10之前的老版本：

$ sudo apt-get install python-setuptools python-dev build-essential

$ sudo easy_install pip

$ sudo pip install --upgrade virtualenv
升级成功之后，继续执行python脚本，还是出错：

AttributeError: 'module' object has no attribute 'Connection'
表示没有 Connection ，pymongo升级完之后不支持了，看手册，发现用MongoClient 来替换了Connection。修改脚本：

conn   = pymongo.Connection(host='127.0.0.1',port=27017)
改成
conn   = pymongo.MongoClient(host='127.0.0.1',port=27017)
 最后执行python，正常。

三，python 操作 Redis:详情见这里

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#!/bin/env python
# -*- encoding: utf-8 -*-
#-------------------------------------------------------------------------------
# Purpose:     example for python_to_mongodb
# Author:      zhoujy
# Created:     2013-06-14
# update:      2013-06-14
#-------------------------------------------------------------------------------

import redis

f = open('aa.txt')
while True:
    line = f.readline().strip().split(' # ')
    if line == ['']:
        break
    UserName,Pwd,Email = line
#    print name.strip(),pwd.strip(),email.strip()
    rc = redis.StrictRedis(host='127.0.0.1',port=6379,db=15)
    rc.hset('Name:' + UserName,'Email',Email)
    rc.hset('Name:' + UserName,'Password',Pwd)
f.close()

alluser = rc.keys('*')
#print alluser
print "===================================读出存进去的数据==================================="
for user in alluser:
    print ' # '.join((user.split(':')[1],rc.hget(user,'Password'),rc.hget(user,'Email')))

四，python 操作 memcache:详情见这里

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import memcache
mc = memcache.Client(['127.0.0.1:11211'],debug=1)
#!/usr/bin/env python
#coding=utf-8
import MySQLdb
import memcache
import sys
import time

def get_data(mysql_conn):
#    nn = raw_input("press string name:")
    mc = memcache.Client(['127.0.0.1:11211'],debug=1)
    t1 =time.time()
    value = mc.get('zhoujinyia')
    if value == None:
        t1 = time.time()
        print t1
        query = "select company,email,sex,address from uc_user_offline where realName = 'zhoujinyia'"
        cursor= mysql_conn.cursor()
        cursor.execute(query)
        item = cursor.fetchone()
        t2 = time.time()
        print t2
        t = round(t2-t1)
        print "from mysql cost %s sec" %t
        print item
        mc.set('zhoujinyia',item,60)
    else :
        t2 = time.time()
        t=round(t2-t1)
        print "from memcache cost %s sec" %t
        print value
if __name__ =='__main__':
    mysql_conn = MySQLdb.connect(host='127.0.0.1',user='root',passwd='123456',db='member',port=3306,charset='utf8')
    get_data(mysql_conn)

Note: 上面介绍了一些python连接数据库，大部分的操作没有列出来，具体的请见各官网。