Python：使用psycopg2模块操作PostgreSQL

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：

 1 import os 2 import sys 3 import psycopg2 4  5 def connectPostgreSQL(): 6     conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432") 7     print 'connect successful!' 8      9 if __name__=='__main__':10     connectPostgreSQL()11     

• 创建表操作：

 1 import os 2 import sys 3 import psycopg2 4  5 def connectPostgreSQL(): 6     conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432") 7     print 'connect successful!' 8     cursor=conn.cursor() 9     cursor.execute('''create table public.member(10 id integer not null primary key,11 name varchar(32) not null,12 password varchar(32) not null,13 singal varchar(128)14 )''')15     conn.commit()16     conn.close()17     print 'table public.member is created!'18     19 if __name__=='__main__':20     connectPostgreSQL()21     

• Insert 操作：

 1 import os 2 import sys 3 import psycopg2 4  5 def connectPostgreSQL(): 6     conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432") 7     print 'connect successful!' 8     cursor=conn.cursor() 9     cursor.execute('''create table public.member(10 id integer not null primary key,11 name varchar(32) not null,12 password varchar(32) not null,13 singal varchar(128)14 )''')15     conn.commit()16     conn.close()17     print 'table public.member is created!'18 19 def insertOperate():20     conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432")21     cursor=conn.cursor()22     cursor.execute("insert into public.member(id,name,password,singal)\23 values(1,'member0','password0','signal0')")24     cursor.execute("insert into public.member(id,name,password,singal)\25 values(2,'member1','password1','signal1')")26     cursor.execute("insert into public.member(id,name,password,singal)\27 values(3,'member2','password2','signal2')")28     cursor.execute("insert into public.member(id,name,password,singal)\29 values(4,'member3','password3','signal3')")30     conn.commit()31     conn.close()32     33     print 'insert records into public.memmber successfully'34     35 if __name__=='__main__':36     #connectPostgreSQL()37     insertOperate()38     

• Select 操作：

 1 import os 2 import sys 3 import psycopg2 4  5 def connectPostgreSQL(): 6     conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432") 7     print 'connect successful!' 8     cursor=conn.cursor() 9     cursor.execute('''create table public.member(10 id integer not null primary key,11 name varchar(32) not null,12 password varchar(32) not null,13 singal varchar(128)14 )''')15     conn.commit()16     conn.close()17     print 'table public.member is created!'18 19 def insertOperate():20     conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432")21     cursor=conn.cursor()22     cursor.execute("insert into public.member(id,name,password,singal)\23 values(1,'member0','password0','signal0')")24     cursor.execute("insert into public.member(id,name,password,singal)\25 values(2,'member1','password1','signal1')")26     cursor.execute("insert into public.member(id,name,password,singal)\27 values(3,'member2','password2','signal2')")28     cursor.execute("insert into public.member(id,name,password,singal)\29 values(4,'member3','password3','signal3')")30     conn.commit()31     conn.close()32     33     print 'insert records into public.memmber successfully'34 35 def selectOperate():36     conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432")37     cursor=conn.cursor()38     cursor.execute("select id,name,password,singal from public.member where id>2")39     rows=cursor.fetchall()40     for row in rows:41         print 'id=',row[0], ',name=',row[1],',pwd=',row[2],',singal=',row[3],'\n'42     conn.close()43     44 if __name__=='__main__':45     #connectPostgreSQL()46     #insertOperate()47     selectOperate()48     

结果：

Python 2.7.12 (v2.7.12:d33e0cf91556, Jun 27 2016, 15:24:40) [MSC v.1500 64 bit (AMD64)] on win32Type "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：

 

 1 import os 2 import sys 3 import psycopg2 4  5 def connectPostgreSQL(): 6     conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432") 7     print 'connect successful!' 8     cursor=conn.cursor() 9     cursor.execute('''create table public.member(10 id integer not null primary key,11 name varchar(32) not null,12 password varchar(32) not null,13 singal varchar(128)14 )''')15     conn.commit()16     conn.close()17     print 'table public.member is created!'18 19 def insertOperate():20     conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432")21     cursor=conn.cursor()22     cursor.execute("insert into public.member(id,name,password,singal)\23 values(1,'member0','password0','signal0')")24     cursor.execute("insert into public.member(id,name,password,singal)\25 values(2,'member1','password1','signal1')")26     cursor.execute("insert into public.member(id,name,password,singal)\27 values(3,'member2','password2','signal2')")28     cursor.execute("insert into public.member(id,name,password,singal)\29 values(4,'member3','password3','signal3')")30     conn.commit()31     conn.close()32     33     print 'insert records into public.memmber successfully'34 35 def selectOperate():36     conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432")37     cursor=conn.cursor()38     cursor.execute("select id,name,password,singal from public.member where id>2")39     rows=cursor.fetchall()40     for row in rows:41         print 'id=',row[0], ',name=',row[1],',pwd=',row[2],',singal=',row[3],'\n'42     conn.close()43 44 def updateOperate():45     conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432")46     cursor=conn.cursor()47     cursor.execute("update public.member set name='update ...' where id=2")48     conn.commit()49     print "Total number of rows updated :", cursor.rowcount50 51     cursor.execute("select id,name,password,singal from public.member")52     rows=cursor.fetchall()53     for row in rows:54         print 'id=',row[0], ',name=',row[1],',pwd=',row[2],',singal=',row[3],'\n'55     conn.close()56     57 if __name__=='__main__':58     #connectPostgreSQL()59     #insertOperate()60     #selectOperate()61     updateOperate()

 

结果：

Python 2.7.12 (v2.7.12:d33e0cf91556, Jun 27 2016, 15:24:40) [MSC v.1500 64 bit (AMD64)] on win32Type "copyright", "credits" or "license()" for more information.>>> ========== RESTART: C:\Users\Administrator\Desktop\mutilpleTest.py ==========Total number of rows updated : 1id= 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：

 

 1 import os 2 import sys 3 import psycopg2 4  5 def connectPostgreSQL(): 6     conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432") 7     print 'connect successful!' 8     cursor=conn.cursor() 9     cursor.execute('''create table public.member(10 id integer not null primary key,11 name varchar(32) not null,12 password varchar(32) not null,13 singal varchar(128)14 )''')15     conn.commit()16     conn.close()17     print 'table public.member is created!'18 19 def insertOperate():20     conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432")21     cursor=conn.cursor()22     cursor.execute("insert into public.member(id,name,password,singal)\23 values(1,'member0','password0','signal0')")24     cursor.execute("insert into public.member(id,name,password,singal)\25 values(2,'member1','password1','signal1')")26     cursor.execute("insert into public.member(id,name,password,singal)\27 values(3,'member2','password2','signal2')")28     cursor.execute("insert into public.member(id,name,password,singal)\29 values(4,'member3','password3','signal3')")30     conn.commit()31     conn.close()32     33     print 'insert records into public.memmber successfully'34 35 def selectOperate():36     conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432")37     cursor=conn.cursor()38     cursor.execute("select id,name,password,singal from public.member where id>2")39     rows=cursor.fetchall()40     for row in rows:41         print 'id=',row[0], ',name=',row[1],',pwd=',row[2],',singal=',row[3],'\n'42     conn.close()43 44 def updateOperate():45     conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432")46     cursor=conn.cursor()47     cursor.execute("update public.member set name='update ...' where id=2")48     conn.commit()49     print "Total number of rows updated :", cursor.rowcount50 51     cursor.execute("select id,name,password,singal from public.member")52     rows=cursor.fetchall()53     for row in rows:54         print 'id=',row[0], ',name=',row[1],',pwd=',row[2],',singal=',row[3],'\n'55     conn.close()56 57 def deleteOperate():58     conn = psycopg2.connect(database="testdb", user="postgres", password="new.1234", host="127.0.0.1", port="5432")    59     cursor=conn.cursor()60 61     cursor.execute("select id,name,password,singal from public.member")62     rows=cursor.fetchall()63     for row in rows:64         print 'id=',row[0], ',name=',row[1],',pwd=',row[2],',singal=',row[3],'\n'65 66     print 'begin delete'67     cursor.execute("delete from public.member where id=2")68     conn.commit()   69     print 'end delete'70     print "Total number of rows deleted :", cursor.rowcount71     72     cursor.execute("select id,name,password,singal from public.member")73     rows=cursor.fetchall()74     for row in rows:75         print 'id=',row[0], ',name=',row[1],',pwd=',row[2],',singal=',row[3],'\n'76     conn.close()77     78 if __name__=='__main__':79     #connectPostgreSQL()80     #insertOperate()81     #selectOperate()82     #updateOperate()83     deleteOperate()

 

结果：

Python 2.7.12 (v2.7.12:d33e0cf91556, Jun 27 2016, 15:24:40) [MSC v.1500 64 bit (AMD64)] on win32Type "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 deleteend deleteTotal number of rows deleted : 1id= 1 ,name= member0 ,pwd= password0 ,singal= signal0 id= 3 ,name= member2 ,pwd= password2 ,singal= signal2 id= 4 ,name= member3 ,pwd= password3 ,singal= signal3 >>>