Python 学习笔记 - 操作MySQL

Python里面操作MySQL可以通过两个方式:

pymysql模块

ORM框架的SQLAchemey

本节先学习第一种方式。

学习Python模块之前，首先看看MySQL的基本安装和使用，具体语法可以参考豆子之前的博客http://beanxyz.blog.51cto.com/5570417/1609972

或者官方简介

https://mariadb.com/kb/en/mariadb/basic-sql-statements/

简单的回顾一下基本环境的搭建：

首先安装Mariadb（我的环境是CentOS7）

yum install mariadb*

systemctl start mariadb

配置防火墙

firewall-cmd --add-port=3306/tcp --permanent

systemctl restart firewalld

配置root密码

mysqladmin -u root password 'mysql'

mysql -uroot -p

创建一个测试用的数据库和表

MariaDB [(none)]> create database mydb;

Query OK, 1 row affected (0.00 sec)

MariaDB [(none)]> use mydb

Database changed

MariaDB [mydb]> create table student(id int not null auto_increment,name varchar(10), primary key(id));

Query OK, 0 rows affected (0.04 sec)

MariaDB [mydb]> insert into student(name) values('Jay'),('Bob'),('Alex');

Query OK, 3 rows affected (0.00 sec)

Records: 3  Duplicates: 0  Warnings: 0

MariaDB [mydb]> select * from student;

+----+------+

| id | name |

+----+------+

|  1 | Jay  |

|  2 | Bob  |

|  3 | Alex |

+----+------+

3 rows in set (0.00 sec)

创建一个远程访问的账户

MariaDB [(none)]> create user yli@10.2.100.60;

Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> set password for yli@'10.2.100.60'=password('yli');

Query OK, 0 rows affected (0.01 sec)

MariaDB [(none)]> grant all privileges on mydb.* to yli@10.2.100.60;

Query OK, 0 rows affected (0.00 sec)

然后安装一个图形界面的工具Navicat,绑定数据库

wKioL1gij7nxF_w0AADPQRGw3qE012.png

wKiom1gij7rh9UoaAADlgxB33VI628.png

这样一个基本的测试环境就搭建好了。

现在来看看pymysql的使用。

在我的客户端安装一下pymysql的模块

C:\WINDOWS\system32>pip install pymysql

Collecting pymysql

  Downloading PyMySQL-0.7.9-py3-none-any.whl (78kB)

    100% |################################| 81kB 610kB/s

Installing collected packages: pymysql

Successfully installed pymysql-0.7.9

Python源码演示

查询

#!/usr/bin/env python

# -*- coding:utf-8 -*-

import pymysql

#打开数据库连接

conn = pymysql.connect(host='sydnagios', port=3306, user='yli', passwd='yli', db='mydb')

#创建一个游标对象

cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)

#SQL查询

cursor.execute("select * from student")

# 获取第一行数据

# row_1 = cursor.fetchone()

# print(row_1)

# 获取前n行数据

# row_2 = cursor.fetchmany(3)

# 获取所有数据

row_3 = cursor.fetchall()

print(row_3)

#scroll可以使用相对位置或者绝对位置，这里相对位置（末尾）向上移动2行

cursor.scroll(-2,mode='relative')

row_3 = cursor.fetchall()

print(row_3)

#提交，不然无法保存新的数据

conn.commit()

#关闭游标

cursor.close()

#关闭连接

conn.close()

-----------

[{'id': 1, 'name': 'Jay'}, {'id': 2, 'name': 'Bob'}, {'id': 3, 'name': 'Alex'}]

[{'id': 2, 'name': 'Bob'}, {'id': 3, 'name': 'Alex'}]

修改

#!/usr/bin/env python

# -*- coding:utf-8 -*-

import pymysql

conn = pymysql.connect(host='sydnagios', port=3306, user='yli', passwd='yli', db='mydb')

cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)

cursor.execute("Update student set name='BoB' where id=2")

cursor.execute("select * from student")

row_3 = cursor.fetchall()

print(row_3)

conn.commit()

cursor.close()

conn.close()

----------

[{'id': 1, 'name': 'Chris'}, {'id': 2, 'name': 'BoB'}, {'id': 3, 'name': 'Alex'}]

删除

#!/usr/bin/env python

# -*- coding:utf-8 -*-

import pymysql

conn = pymysql.connect(host='sydnagios', port=3306, user='yli', passwd='yli', db='mydb')

cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)

cursor.execute("delete from student where id=2")

cursor.execute("select * from student")

row_3 = cursor.fetchall()

print(row_3)

conn.commit()

cursor.close()

conn.close()

----------

[{'id': 1, 'name': 'Chris'}, {'id': 2, 'name': 'BoB'}, {'id': 3, 'name': 'Alex'}]

添加

#!/usr/bin/env python

# -*- coding:utf-8 -*-

import pymysql

conn = pymysql.connect(host='sydnagios', port=3306, user='yli', passwd='yli', db='mydb')

cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)

cursor.execute("insert into student(name) value ('ZhangSan'),('LiSi')")

cursor.execute("select * from student")

row_3 = cursor.fetchall()

print(row_3)

conn.commit()

cursor.close()

conn.close()

----------

[{'name': 'Chris', 'id': 1}, {'name': 'Alex', 'id': 3}, {'name': 'ZhangSan', 'id': 4}, {'name': 'LiSi', 'id': 5}]

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