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Python操作PostgreSQL数据库示例【连接、增删改查等】

这篇文章主要介绍了Python操作PostgreSQL数据库的方法,结合实例形式分析了Python连接PostgreSQL及增删改查等相关操作技巧,需要的朋友可以参考下

本文实例讲述了Python 操作 PostgreSQL 数据库。分享给大家供大家参考,具体如下:

我使用的是 Python 3.7.0

PostgreSQL可以使用psycopg2模块与Python集成。

sycopg2是用于Python编程语言的PostgreSQL数据库适配器。

psycopg2是非常小,快速,稳定的。 您不需要单独安装此模块,因为默认情况下它会随着Python 2.5.x版本一起发布。

 pip3 install python-psycopg2 pip3 install psycopg2-binary 

连接到数据库

以下Python代码显示了如何连接到现有的数据库。 如果数据库不存在,那么它将自动创建,最后将返回一个数据库对象。

 #!/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") 

在这里指定使用testdb作为数据库名称,如果数据库已成功打开连接,则会提供以下消息:

Open database successfully

创建表

以下Python程序将用于在先前创建的数据库(testdb)中创建一个表:

 #!/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('''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() 

当执行上述程序时,它将在数据库testdb中创建COMPANY表,并显示以下消息:

Opened database successfully
Table created successfully

插入操作

以下Python程序显示了如何在上述示例中创建的COMPANY表中创建记录:

 #!/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() 

当执行上述程序时,它将在COMPANY表中创建/插入给定的记录,并显示以下两行:

Opened database successfully
Records created successfully

SELECT操作

以下 Python 程序显示了如何从上述示例中创建的 COMPANY 表中获取和显示记录:

 #!/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() 

执行上述程序时,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

更新操作

以下 Python 代码显示了如何使用UPDATE语句来更新任何记录,然后从COMPANY表中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() 

Python

执行上述程序时,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

删除操作

以下 Python 代码显示了如何使用 DELETE 语句来删除记录,然后从 COMPANY 表中获取并显示剩余的记录:

 #!/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() 

执行上述程序时,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

更多关于Python相关内容感兴趣的读者可查看本站专题:《Python常见数据库操作技巧汇总》、《Python数学运算技巧总结》、《Python数据结构与算法教程》、《Python函数使用技巧总结》、《Python字符串操作技巧汇总》、《Python入门与进阶经典教程》及《Python文件与目录操作技巧汇总》

希望本文所述对大家Python程序设计有所帮助。

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