Python中用psycopg2模块操作PostgreSQL方法

其实在Python中可以用来连接PostgreSQL的模块很多，这里比较推荐psycopg2。psycopg2安装起来非常的简单（pip install psycopg2），这里主要重点介绍下如何使用。

安装psycopg2模块：

怎么验证是否已经安装过psycopy2?

编写上面代码，运行看是否抛出缺少psycopg2模块。

安装方法1：

1)使用psycopg2-2.4.2.win-amd64-py2.7-pg9.0.4-release.exe安装，下载地址:http://vdisk.weibo.com/s/Cd8pPaw56Ozys

直接运行exe，不出错误，运行上边代码验证代码无错误，基本算是安装完成了。

2)怎么卸载？

2.1）找到安装目录：C:\Python27，发现下边包含文件:Removepsycopg2.exe,运行，来删除；

2.2）如果运行失败的话，进入目录：C:\Python27\Lib\site-packages下，找到psycopg2文件夹和psycopg2-2.4.2-py2.7.egg-info文件，右键删除。

2.3）运行上边的代码，确认是否删除成功。

安装方法2：

使用.whl安装，下载地址：https://pypi.python.org/pypi/psycopg2/

下载文件：psycopg2-2.6.2-cp27-none-win_amd64.whl

我这里把psycopg2-2.6.2-cp27-none-win_amd64.whl拷贝到安装目录下Scripts文件夹中。

cmd中运行代码：pip install C:\Python27\Scripts\psycopg2-2.6.2-cp27-none-win_amd64.whl

运行上边的代码，确认是否删除成功。

通过psycopg2操作数据库：

使用账户postgres，创建测试数据库testdb。

参考yiibai.comAPI:

S.N. API & 描述

1 psycopg2.connect(database="testdb", user="postgres", password="cohondob", host="127.0.0.1", port="5432")

这个API打开一个连接到PostgreSQL数据库。如果成功打开数据库时，它返回一个连接对象。

2 connection.cursor()

该程序创建一个光标将用于整个数据库使用Python编程。

3 cursor.execute(sql [, optional parameters])

此例程执行SQL语句。可被参数化的SQL语句（即占位符，而不是SQL文字）。 psycopg2的模块支持占位符用％s标志

例如：cursor.execute("insert into people values (%s, %s)", (who, age))

4 curosr.executemany(sql, seq_of_parameters)

该程序执行SQL命令对所有参数序列或序列中的sql映射。

5 curosr.callproc(procname[, parameters])

这个程序执行的存储数据库程序给定的名称。该程序预计为每一个参数，参数的顺序必须包含一个条目。

6 cursor.rowcount

这个只读属性，它返回数据库中的行的总数已修改，插入或删除最后 execute*().

7 connection.commit()

此方法提交当前事务。如果不调用这个方法，无论做了什么修改，自从上次调用commit()是不可见的，从其他的数据库连接。

8 connection.rollback()

此方法会回滚任何更改数据库自上次调用commit（）方法。

9 connection.close()

此方法关闭数据库连接。请注意，这并不自动调用commit（）。如果你只是关闭数据库连接而不调用commit（）方法首先，那么所有更改将会丢失！

10 cursor.fetchone()

这种方法提取的查询结果集的下一行，返回一个序列，或者无当没有更多的数据是可用的。

11 cursor.fetchmany([size=cursor.arraysize])

这个例程中取出下一个组的查询结果的行数，返回一个列表。当没有找到记录，返回空列表。该方法试图获取尽可能多的行所显示的大小参数。

12 cursor.fetchall()

这个例程获取所有查询结果（剩余）行，返回一个列表。空行时则返回空列表。

打开数据库连接：

import os import sys import psycopg2 def connectPostgreSQL(): conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432") print 'connect successful!' if __name__=='__main__': connectPostgreSQL()

创建表操作：

import os import sys import psycopg2 def connectPostgreSQL(): conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432") print 'connect successful!' cursor=conn.cursor() cursor.execute('''create table public.member( id integer not null primary key, name varchar(32) not null, password varchar(32) not null, singal varchar(128) )''') conn.commit() conn.close() print 'table public.member is created!' if __name__=='__main__': connectPostgreSQL()

Insert 操作：

import os import sys import psycopg2 def connectPostgreSQL(): conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432") print 'connect successful!' cursor=conn.cursor() cursor.execute('''create table public.member( id integer not null primary key, name varchar(32) not null, password varchar(32) not null, singal varchar(128) )''') conn.commit() conn.close() print 'table public.member is created!' def insertOperate(): conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432") cursor=conn.cursor() cursor.execute("insert into public.member(id,name,password,singal)\ values(1,'member0','password0','signal0')") cursor.execute("insert into public.member(id,name,password,singal)\ values(2,'member1','password1','signal1')") cursor.execute("insert into public.member(id,name,password,singal)\ values(3,'member2','password2','signal2')") cursor.execute("insert into public.member(id,name,password,singal)\ values(4,'member3','password3','signal3')") conn.commit() conn.close() print 'insert records into public.memmber successfully' if __name__=='__main__': #connectPostgreSQL() insertOperate()

Select 操作：

import os import sys import psycopg2 def connectPostgreSQL(): conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432") print 'connect successful!' cursor=conn.cursor() cursor.execute('''create table public.member( id integer not null primary key, name varchar(32) not null, password varchar(32) not null, singal varchar(128) )''') conn.commit() conn.close() print 'table public.member is created!' def insertOperate(): conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432") cursor=conn.cursor() cursor.execute("insert into public.member(id,name,password,singal)\ values(1,'member0','password0','signal0')") cursor.execute("insert into public.member(id,name,password,singal)\ values(2,'member1','password1','signal1')") cursor.execute("insert into public.member(id,name,password,singal)\ values(3,'member2','password2','signal2')") cursor.execute("insert into public.member(id,name,password,singal)\ values(4,'member3','password3','signal3')") conn.commit() conn.close() print 'insert records into public.memmber successfully' def selectOperate(): conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432") cursor=conn.cursor() cursor.execute("select id,name,password,singal from public.member where id>2") rows=cursor.fetchall() for row in rows: print 'id=',row[0], ',name=',row[1],',pwd=',row[2],',singal=',row[3],'\n' conn.close() if __name__=='__main__': #connectPostgreSQL() #insertOperate() selectOperate()

结果：

Python 2.7.12 (v2.7.12:d33e0cf91556, Jun 27 2016, 15:24:40) [MSC v.1500 64 bit (AMD64)] on win32 Type "copyright", "credits" or "license()" for more information. >>> ========== RESTART: C:\Users\Administrator\Desktop\mutilpleTest.py ========== id= 3 ,name= member2 ,pwd= password2 ,singal= signal2 id= 4 ,name= member3 ,pwd= password3 ,singal= signal3 >>>

update操作：

import os import sys import psycopg2 def connectPostgreSQL(): conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432") print 'connect successful!' cursor=conn.cursor() cursor.execute('''create table public.member( id integer not null primary key, name varchar(32) not null, password varchar(32) not null, singal varchar(128) )''') conn.commit() conn.close() print 'table public.member is created!' def insertOperate(): conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432") cursor=conn.cursor() cursor.execute("insert into public.member(id,name,password,singal)\ values(1,'member0','password0','signal0')") cursor.execute("insert into public.member(id,name,password,singal)\ values(2,'member1','password1','signal1')") cursor.execute("insert into public.member(id,name,password,singal)\ values(3,'member2','password2','signal2')") cursor.execute("insert into public.member(id,name,password,singal)\ values(4,'member3','password3','signal3')") conn.commit() conn.close() print 'insert records into public.memmber successfully' def selectOperate(): conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432") cursor=conn.cursor() cursor.execute("select id,name,password,singal from public.member where id>2") rows=cursor.fetchall() for row in rows: print 'id=',row[0], ',name=',row[1],',pwd=',row[2],',singal=',row[3],'\n' conn.close() def updateOperate(): conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432") cursor=conn.cursor() cursor.execute("update public.member set name='update ...' where id=2") conn.commit() print "Total number of rows updated :", cursor.rowcount cursor.execute("select id,name,password,singal from public.member") rows=cursor.fetchall() for row in rows: print 'id=',row[0], ',name=',row[1],',pwd=',row[2],',singal=',row[3],'\n' conn.close() if __name__=='__main__': #connectPostgreSQL() #insertOperate() #selectOperate() updateOperate()

结果：

Python 2.7.12 (v2.7.12:d33e0cf91556, Jun 27 2016, 15:24:40) [MSC v.1500 64 bit (AMD64)] on win32 Type "copyright", "credits" or "license()" for more information. >>> ========== RESTART: C:\Users\Administrator\Desktop\mutilpleTest.py ========== Total number of rows updated : 1 id= 1 ,name= member0 ,pwd= password0 ,singal= signal0 id= 3 ,name= member2 ,pwd= password2 ,singal= signal2 id= 4 ,name= member3 ,pwd= password3 ,singal= signal3 id= 2 ,name= update ... ,pwd= password1 ,singal= signal1 >>>

Delete操作：

import os import sys import psycopg2 def connectPostgreSQL(): conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432") print 'connect successful!' cursor=conn.cursor() cursor.execute('''create table public.member( id integer not null primary key, name varchar(32) not null, password varchar(32) not null, singal varchar(128) )''') conn.commit() conn.close() print 'table public.member is created!' def insertOperate(): conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432") cursor=conn.cursor() cursor.execute("insert into public.member(id,name,password,singal)\ values(1,'member0','password0','signal0')") cursor.execute("insert into public.member(id,name,password,singal)\ values(2,'member1','password1','signal1')") cursor.execute("insert into public.member(id,name,password,singal)\ values(3,'member2','password2','signal2')") cursor.execute("insert into public.member(id,name,password,singal)\ values(4,'member3','password3','signal3')") conn.commit() conn.close() print 'insert records into public.memmber successfully' def selectOperate(): conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432") cursor=conn.cursor() cursor.execute("select id,name,password,singal from public.member where id>2") rows=cursor.fetchall() for row in rows: print 'id=',row[0], ',name=',row[1],',pwd=',row[2],',singal=',row[3],'\n' conn.close() def updateOperate(): conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432") cursor=conn.cursor() cursor.execute("update public.member set name='update ...' where id=2") conn.commit() print "Total number of rows updated :", cursor.rowcount cursor.execute("select id,name,password,singal from public.member") rows=cursor.fetchall() for row in rows: print 'id=',row[0], ',name=',row[1],',pwd=',row[2],',singal=',row[3],'\n' conn.close() def deleteOperate(): conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432") cursor=conn.cursor() cursor.execute("select id,name,password,singal from public.member") rows=cursor.fetchall() for row in rows: print 'id=',row[0], ',name=',row[1],',pwd=',row[2],',singal=',row[3],'\n' print 'begin delete' cursor.execute("delete from public.member where id=2") conn.commit() print 'end delete' print "Total number of rows deleted :", cursor.rowcount cursor.execute("select id,name,password,singal from public.member") rows=cursor.fetchall() for row in rows: print 'id=',row[0], ',name=',row[1],',pwd=',row[2],',singal=',row[3],'\n' conn.close() if __name__=='__main__': #connectPostgreSQL() #insertOperate() #selectOperate() #updateOperate() deleteOperate()

结果：

Python 2.7.12 (v2.7.12:d33e0cf91556, Jun 27 2016, 15:24:40) [MSC v.1500 64 bit (AMD64)] on win32 Type "copyright", "credits" or "license()" for more information. >>> ========== RESTART: C:\Users\Administrator\Desktop\mutilpleTest.py ========== id= 1 ,name= member0 ,pwd= password0 ,singal= signal0 id= 3 ,name= member2 ,pwd= password2 ,singal= signal2 id= 4 ,name= member3 ,pwd= password3 ,singal= signal3 id= 2 ,name= update ... ,pwd= password1 ,singal= signal1 begin delete end delete Total number of rows deleted : 1 id= 1 ,name= member0 ,pwd= password0 ,singal= signal0 id= 3 ,name= member2 ,pwd= password2 ,singal= signal2 id= 4 ,name= member3 ,pwd= password3 ,singal= signal3 >>>

您可能感兴趣的文章:python使用 request 发送表单数据操作示例Python mutiprocessing多线程池pool操作示例Python编程在flask中模拟进行Restful的CRUD操作python3+requests接口自动化session操作方法Python读取properties配置文件操作示例使用Python对Access读写操作Python操作Access数据库基本步骤分析python进程类subprocess的一些操作方法例子Python使用PyGreSQL操作PostgreSQL数据库教程基于python操作ES实例详解

psycopg2 模块 PostgreSQL Python