Python：使用psycopg2模块操作PostgreSQL

安装psycopg2模块：

postgresql client ---Navicat Premium

• 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:Python27Libsite-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:Python27Scriptspsycopg2-2.6.2-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],'
'
    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:UsersAdministratorDesktopmutilpleTest.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],'
'
    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],'
'
    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:UsersAdministratorDesktopmutilpleTest.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],'
'
    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],'
'
    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],'
'

    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],'
'
    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:UsersAdministratorDesktopmutilpleTest.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 

>>> 

 

参考文章：

http://www.cnblogs.com/qiongmiaoer/archive/2013/09/30/3346984.html

http://www.yiibai.com/html/postgresql/2013/080998.html