PostgreSQL可以用Python psycopg2模块集成。 sycopg2是Python编程语言的PostgreSQL数据库的适配器。 其程序代码少，速度快，稳定。不需要单独安装这个模块，因为它默认情况下被运往随着Python版本在2.5.x一起的。如果不把它安装在机器上，然后可以使用yum命令安装它，如下所示：

$yum install python-psycopg2

要使用psycopg2的模块，首先必须创建一个Connection对象，它表示数据库然后再可以选择创建游标对象，这将帮助执行的所有SQL语句。

Python psycopg2 模块APIs

以下是psycopg2的重要的的模块例程可以满足Python程序与PostgreSQL数据库的工作。如果寻找一个更复杂的应用程序，那么可以看看Python psycopg2的模块的官方文档。

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。

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))

import psycopg2 conn = psycopg2.connect(database= " testdb " , user= " postgres " , password= " pass123 " , host= " 127.0.0.1 " , port= " 5432 " ) print " Opened database successfully " cur = conn.cursor() cur.execute( ''' CREATE TABLE COMPANY (ID INT PRIMARY KEY NOT NULL, NAME TEXT NOT NULL, AGE INT NOT NULL, ADDRESS CHAR(50), SALARY REAL); ''' ) print " Table created successfully " conn.commit() conn.close()

上述程序执行时，它会创建表COMPANY 在数据库test.db中，它会显示以下消息：

Opened database successfully
Table created successfully

INSERT 操作

Python程序显示了我们如何创建表COMPANY 在上面的例子中创建表中的记录：

#!/usr/bin/python
import psycopg2
conn = psycopg2.connect(database="testdb", user="postgres", password="pass123", host="127.0.0.1", port="5432")
print "Opened database successfully"
cur = conn.cursor()
cur.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) \
      VALUES (1, 'Paul', 32, 'California', 20000.00 )");
cur.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) \
      VALUES (2, 'Allen', 25, 'Texas', 15000.00 )");
cur.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) \
      VALUES (3, 'Teddy', 23, 'Norway', 20000.00 )");
cur.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) \
      VALUES (4, 'Mark', 25, 'Rich-Mond ', 65000.00 )");
conn.commit()
print "Records created successfully";
conn.close() yiibai.com 

上述程序执行时，它会创建COMPANY表中的记录，并显示以下两行：

Opened database successfully
Records created successfully

SELECT 操作

Python程序，显示如何获取并显示COMPANY 表在上面的例子中创建的记录：

#!/usr/bin/python
import psycopg2
conn = psycopg2.connect(database="testdb", user="postgres", password="pass123", host="127.0.0.1", port="5432")
print "Opened database successfully"
cur = conn.cursor()
cur.execute("SELECT id, name, address, salary  from COMPANY")
rows = cur.fetchall()
for row in rows:
   print "ID = ", row[0]
   print "NAME = ", row[1]
   print "ADDRESS = ", row[2]
   print "SALARY = ", row[3], "\n"
print "Operation done successfully";
conn.close()  

当上述程序执行时，它会产生以下结果：

Opened database successfully
ID =  1
NAME =  Paul
ADDRESS =  California
SALARY =  20000.0
ID =  2
NAME =  Allen
ADDRESS =  Texas
SALARY =  15000.0
ID =  3
NAME =  Teddy
ADDRESS =  Norway
SALARY =  20000.0
ID =  4
NAME =  Mark
ADDRESS =  Rich-Mond
SALARY =  65000.0
Operation done successfully

UPDATE 操作

Python代码显示如何，我们可以使用UPDATE语句来更新记录，然后从COMPANY表获取并显示更新的记录：

#!/usr/bin/python
import psycopg2
conn = psycopg2.connect(database="testdb", user="postgres", password="pass123", host="127.0.0.1", port="5432")
print "Opened database successfully"
cur = conn.cursor()
cur.execute("UPDATE COMPANY set SALARY = 25000.00 where ID=1")
conn.commit
print "Total number of rows updated :", cur.rowcount
cur.execute("SELECT id, name, address, salary  from COMPANY")
rows = cur.fetchall()
for row in rows:
   print "ID = ", row[0]
   print "NAME = ", row[1]
   print "ADDRESS = ", row[2]
   print "SALARY = ", row[3], "\n"
print "Operation done successfully";
conn.close() 

当上述程序执行时，它会产生以下结果：

Opened database successfully
Total number of rows updated : 1
ID =  1
NAME =  Paul
ADDRESS =  California
SALARY =  25000.0
ID =  2
NAME =  Allen
ADDRESS =  Texas
SALARY =  15000.0
ID =  3
NAME =  Teddy
ADDRESS =  Norway
SALARY =  20000.0
ID =  4
NAME =  Mark
ADDRESS =  Rich-Mond
SALARY =  65000.0
Operation done successfully

DELETE 操作

Python代码显示了如何我们可以使用DELETE语句删除记录，然后获取并显示COMPANY 表剩余的记录：

#!/usr/bin/python
import psycopg2
conn = psycopg2.connect(database="testdb", user="postgres", password="pass123", host="127.0.0.1", port="5432")
print "Opened database successfully"
cur = conn.cursor()
cur.execute("DELETE from COMPANY where ID=2;")
conn.commit
print "Total number of rows deleted :", cur.rowcount
cur.execute("SELECT id, name, address, salary  from COMPANY")
rows = cur.fetchall()
for row in rows:
   print "ID = ", row[0]
   print "NAME = ", row[1]
   print "ADDRESS = ", row[2]
   print "SALARY = ", row[3], "\n"
print "Operation done successfully";
conn.close()  

当上述程序执行时，它会产生以下结果：
Opened database successfully
Total number of rows deleted : 1
ID =  1
NAME =  Paul
ADDRESS =  California
SALARY =  20000.0
ID =  3
NAME =  Teddy
ADDRESS =  Norway
SALARY =  20000.0
ID =  4
NAME =  Mark
ADDRESS =  Rich-Mond
SALARY =  65000.0
Operation done successfully