Python：使用psycopg2模塊操作PostgreSQL

安裝psycopg2模塊：

postgresql client ---Navicat Premium

• 怎么驗證是否已經安裝過psycopy2?

 

編寫上面代碼，運行看是否拋出缺少psycopg2模塊。

• 安裝方法1：

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

直接運行exe，不出錯誤，運行上邊代碼驗證代碼無錯誤，基本算是安裝完成了。

2)怎么卸載？

2.1）找到安裝目錄：C:\Python27，發現下邊包含文件:Removepsycopg2.exe,運行，來刪除；

2.2）如果運行失敗的話，進入目錄：C:\Python27\Lib\site-packages下，找到psycopg2文件夾和psycopg2-2.4.2-py2.7.egg-info文件，右鍵刪除。

2.3）運行上邊的代碼，確認是否刪除成功。

• 安裝方法2：

使用.whl安裝，下載地址：https://pypi.python.org/pypi/psycopg2/

下載文件：psycopg2-2.6.2-cp27-none-win_amd64.whl

我這里把psycopg2-2.6.2-cp27-none-win_amd64.whl拷貝到安裝目錄下Scripts文件夾中。

cmd中運行代碼：pip install C:\Python27\Scripts\psycopg2-2.6.2-cp27-none-win_amd64.whl

運行上邊的代碼，確認是否刪除成功。

•  通過psycopg2操作數據庫：

使用賬戶postgres，創建測試數據庫testdb。

參考yiibai.comAPI:

S.N. API & 描述
1 psycopg2.connect(database="testdb", user="postgres", password="cohondob", host="127.0.0.1", port="5432")
　　這個API打開一個連接到PostgreSQL數據庫。如果成功打開數據庫時，它返回一個連接對象。
2 connection.cursor()
　　該程序創建一個光標將用於整個數據庫使用Python編程。
3 cursor.execute(sql [, optional parameters])
　　此例程執行SQL語句。可被參數化的SQL語句（即占位符，而不是SQL文字）。 psycopg2的模塊支持占位符用％s標志
　　例如：cursor.execute("insert into people values (%s, %s)", (who, age))
4 curosr.executemany(sql, seq_of_parameters)
　　該程序執行SQL命令對所有參數序列或序列中的sql映射。
5 curosr.callproc(procname[, parameters])
　　這個程序執行的存儲數據庫程序給定的名稱。該程序預計為每一個參數，參數的順序必須包含一個條目。
6 cursor.rowcount
　　這個只讀屬性，它返回數據庫中的行的總數已修改，插入或刪除最后 execute*().
7 connection.commit()
　　此方法提交當前事務。如果不調用這個方法，無論做了什么修改，自從上次調用commit()是不可見的，從其他的數據庫連接。
8 connection.rollback()
　　此方法會回滾任何更改數據庫自上次調用commit（）方法。
9 connection.close()
　　此方法關閉數據庫連接。請注意，這並不自動調用commit（）。如果你只是關閉數據庫連接而不調用commit（）方法首先，那么所有更改將會丟失！
10 cursor.fetchone()
　　這種方法提取的查詢結果集的下一行，返回一個序列，或者無當沒有更多的數據是可用的。
11 cursor.fetchmany([size=cursor.arraysize])
　　這個例程中取出下一個組的查詢結果的行數，返回一個列表。當沒有找到記錄，返回空列表。該方法試圖獲取盡可能多的行所顯示的大小參數。
12 cursor.fetchall()
　　這個例程獲取所有查詢結果（剩余）行，返回一個列表。空行時則返回空列表。

• 打開數據庫連接：

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()
    

• 創建表操作：

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()
    

結果：

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()

 

結果：

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()

 

結果：

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 

>>> 

 

 

 

 

參考文章：

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

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