欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识！
您现在的位置是： 首页  >  IT编程

Python中用psycopg2模块操作PostgreSQL方法

程序员文章站 2022-03-30 09:30:43
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）...

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?

Python中用psycopg2模块操作PostgreSQL方法

编写上面代码，运行看是否抛出缺少psycopg2模块。

Python中用psycopg2模块操作PostgreSQL方法

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/

Python中用psycopg2模块操作PostgreSQL方法

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

Python中用psycopg2模块操作PostgreSQL方法

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。

Python中用psycopg2模块操作PostgreSQL方法

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 

>>>

Python中用psycopg2模块操作PostgreSQL方法

上一篇： Python：Pandas详细总结

下一篇： 面试题-null和undefined的区别

推荐阅读