python 連接操作 各類數據庫

摘要：

      用Python寫腳本也有一段時間了，經常操作數據庫（MySQL），現在就整理下對各類數據庫的操作，如后面有新的參數會補進來，慢慢完善。

一，python 操作 MySQL:詳情見：這里

mac 安裝：http://sourceforge.net/projects/mysql-python/?source=dlp  再  sudo python setup.py build

【apt-get install python-mysqldb】

【yum install python-devel  & pip install MySQL-python】

#!/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

#建立和數據庫系統的連接，格式
#conn   = MySQLdb.connect(host='localhost',user='root',passwd='123456',db='test',port=3306,charset='utf8')

#指定配置文件，確定目錄,或則寫絕對路徑
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')

#要執行的sql語句
query  = 'select id  from t1'

#獲取操作游標
cursor = conn.cursor() #執行SQL
cursor.execute(query) #獲取一條記錄,每條記錄做為一個元組返回,返回3，游標指到第2條記錄。
result1 = cursor.fetchone() for i in result1:
    print i
#返回影響的行數
    print cursor.rowcount #獲取指定數量記錄,每條記錄做為一個元組返回,返回1，2，游標從第2條記錄開始，游標指到第4條記錄。
result2 = cursor.fetchmany(2) for i in result2:
    for ii in i:
        print ii


#獲取所有記錄,每條記錄做為一個元組返回,返回3，4，7，6,游標從第4條記錄開始到最后。
result3 = cursor.fetchall() for i in result3:
    for ii in i:
        print ii

#獲取所有記錄,每條記錄做為一個元組返回,返回3，4，7，6,游標從第1條記錄開始
#重置游標位置，0為偏移量，mode＝absolute | relative,默認為relative
cursor.scroll(0,mode='absolute')
result3 = cursor.fetchall()
for i in result3:
    for ii in i:
        print ii

#以下2種方法都可以把數據插入數據庫：
#(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個參數,第2個參數是變量。
cursor.executemany(query2,rows) #提交
conn.commit()

#選擇數據庫
query3 = 'select id from dba_hospital'
#重新選擇數據庫
conn.select_db('chushihua')

cursor.execute(query3)

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

#關閉游標，釋放資源
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：在腳本中，密碼寫在腳本里面很容易暴露，這樣可以用一個配置文件的方式來存密碼，如db.conf：

[client]
user=root
password=123456

二，python 操作 MongoDB:詳情見這里和這里以及這里

#!/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

#建立和數據庫系統的連接,創建Connection時，指定host及port參數
conn   = pymongo.Connection(host='127.0.0.1',port=27017)

#admin 數據庫有帳號，連接-認證-切換庫
db_auth = conn.admin
db_auth.authenticate('sa','sa')
#連接數據庫
db = conn.abc

#連接表
collection = db.stu

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

#訪問表的數據，指定列
item = collection.find({},{"sname":1,"course":1,"_id":0})
for rows in item:
    print rows.values()

#訪問表的一行數據
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)

#得到行數
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，第一個參數是條件，第二個參數是更新操作，$set,%inc,$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)

#刪除，第一個參數是條件，第二個參數是刪除操作。
collection.remove({"sno":101})

'''
sno:學號；sname：姓名；course：科目

db.stu.insert({"sno":1,"sname":"張三","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":"趙五","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":"楊六","course":{"A":65,"U":80,"C":78,"R":75,"N":90}})
db.stu.insert({"sno":7,"sname":"陳二","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}})

'''

計算Mongodb文檔中各集合的數目：

import pymongo

conn   = pymongo.Connection(host='127.0.0.1',port=27017)
db = conn.abc    #abc文檔
for tb_name in db.collection_names():     #循環出各集合名
    Count = db[tb_name].count()            #計算各集合的數量
    if Count > 2:                                 #過濾條件
        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()')      #變量當集合的處理方式

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')

'''

updatetime: 2015-06-30

MongoDB升級到了3.0之后，用python的連接會出錯：

pymongo.errors.OperationFailure: command SON([('authenticate', 1), ('user', u'dba'), ('nonce', u'8c7842b068e14d3'), ('key', u'584ec63f1cdfd8525ce33d99cd269c2c')]) failed: auth failed

表示認證失敗，說明MongoDB升級之后，對用用戶的加密方式改變了。那就升級pymongo。

zhoujy@zhoujy:~$ sudo pip install pymongo --upgrade
[sudo] password for zhoujy:
...
...
Successfully installed pymongo
Cleaning up...

升級成功，要是沒有安裝pip，看這里：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 

升級成功之后，繼續執行python腳本，還是出錯：

AttributeError: 'module' object has no attribute 'Connection'

表示沒有 Connection ，pymongo升級完之后不支持了，看手冊，發現用MongoClient 來替換了Connection。修改腳本：

conn   = pymongo.Connection(host='127.0.0.1',port=27017)
改成
conn   = pymongo.MongoClient(host='127.0.0.1',port=27017)

 最后執行python，正常。

三，python 操作 Redis:詳情見這里 和 這里/這里；集群連接

#!/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 "===================================讀出存進去的數據==================================="
for user in alluser:
    print ' # '.join((user.split(':')[1],rc.hget(user,'Password'),rc.hget(user,'Email'))) 

一個pipeline的請看：這里

四，python 操作 memcache:詳情見 這里 和 這里

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)

上面介紹了一些python連接數據庫，紅色部分是連接操作的關鍵部分，大部分的操作沒有列出來，具體的請見各官網。