Python操作MySQL：pymysql和SQLAlchemy

本篇对于Python操作MySQL主要使用两种方式：

• 原生模块 pymsql
• ORM框架 SQLAchemy

 

pymsql是Python中操作MySQL的模块，其使用方法和MySQLdb几乎相同。

下载安装

pip3 install pymysql

使用操作

1、执行SQL

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import pymysql
  
# 创建连接
conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1')
# 创建游标
cursor = conn.cursor()
  
# 执行SQL，并返回收影响行数
effect_row = cursor.execute("update hosts set host = '1.1.1.2'")
  
# 执行SQL，并返回受影响行数
#effect_row = cursor.execute("update hosts set host = '1.1.1.2' where nid > %s", (1,))
  
# 执行SQL，并返回受影响行数
#effect_row = cursor.executemany("insert into hosts(host,color_id)values(%s,%s)", [("1.1.1.11",1),("1.1.1.11",2)])
  
  
# 提交，不然无法保存新建或者修改的数据
conn.commit()
  
# 关闭游标
cursor.close()
# 关闭连接
conn.close()

示例:

import pymysql


conn = pymysql.connect(host="10.37.129.3",port=3306,user="egon",passwd="123456",db="homework",charset="utf8")

cursor = conn.cursor()


#方式一:

sql = "select * from course where cid=1"
effect_row = cursor.execute(sql)


# 方式二：
sql = "select * from course where cid='%s'" %(1,)
effect_row = cursor.execute(sql)


# 方式三  普通  列表
sql = "select * from course where cid='%s'"

effect_row = cursor.execute(sql,1)
effect_row = cursor.execute(sql,[1])


# 方式四  字典格式

sql = "select * from course where cid='%(u)s'"
effect_row = cursor.execute(sql,{"u":1})


row_1 = cursor.fetchone()

cursor.close()
conn.close()

print(row_1)

2、获取新创建数据自增ID

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import pymysql
  
conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1')
cursor = conn.cursor()
cursor.executemany("insert into hosts(host,color_id)values(%s,%s)", [("1.1.1.11",1),("1.1.1.11",2)])
conn.commit()
cursor.close()
conn.close()
  
# 获取最新自增ID
new_id = cursor.lastrowid

3、获取查询数据

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import pymysql
  
conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1')
cursor = conn.cursor()
cursor.execute("select * from hosts")
  
# 获取第一行数据
row_1 = cursor.fetchone()
  
# 获取前n行数据
# row_2 = cursor.fetchmany(3)
# 获取所有数据
# row_3 = cursor.fetchall()
  
conn.commit()
cursor.close()
conn.close()

注：在fetch数据时按照顺序进行，可以使用cursor.scroll(num,mode)来移动游标位置，如：

• cursor.scroll(1,mode='relative')  # 相对当前位置移动
• cursor.scroll(2,mode='absolute') # 相对绝对位置移动

4、fetch数据类型

　　关于默认获取的数据是元祖类型，如果想要或者字典类型的数据，即：

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import pymysql
  
conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1')
  
# 游标设置为字典类型
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
r = cursor.execute("call p1()")
  
result = cursor.fetchone()
  
conn.commit()
cursor.close()
conn.close()

 5、插入演示

import pymysql


conn = pymysql.connect(host="10.37.129.3",port=3306,user="egon",passwd="123456",db="student_info",charset="utf8")

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


#插入一行
# sql = "insert into student_info(sname,gender,class_id) VALUES('alex1','女',2)"

#插入多行
sql = "insert into student_info(sname,gender,class_id) VALUES('alex1','女',2),('alex2','女',2),('alex3','女',2)"

r = cursor.execute(sql)

#或

sql = "insert into userinfo(username,password) values(%s,%s)"
# 受影响的行数
r = cursor.executemany(sql,[('egon','sb'),('laoyao','BS')])




conn.commit()
cursor.close()
conn.close()

print(r)

 

 

6、补充

# sql 注入
import pymysql

user = input("username:")
pwd = input("password:")

conn = pymysql.connect(host="localhost",user='root',password='',database="db3")   #建立与客户端的链接
cursor = conn.cursor()
sql = "select * from userinfo where username='%s' and pwd='%s'" %(user,pwd,) #不要自己定义放置占位符user和pwd，防数据库被泄露
# select * from userinfo where username='uu' or 1=1 -- ' and password='%s'
#上面部分会理解成，第一部分：select * from userinfo where username='uu'，第二部分：or 1=1，第三部分：-- 注释，
# 第四部分：' and password='%s'，第四部分会当成注释内容。所以执行该程序会显示登录成功。
cursor.execute(sql)         #执行sql语句
result = cursor.fetchone()  #返回第一行内容
#关闭连接
cursor.close()
conn.close()

if result:
    print('登录成功')
else:
    print('登录失败')

 

import pymysql
user = input("username:")
pwd = input("password:")

conn = pymysql.connect(host="localhost",user='root',password='',database="db3")
cursor = conn.cursor()
sql = "select * from userinfo where username=%s and pwd=%s"
# cursor.execute(sql,(user,pwd))
cursor.execute(sql,[user,pwd])    #cursor.execute(sql,user,pwd)也可写成cursor.execute(sql,[user,pwd])，效果一样
# cursor.execute(sql,{'u':user,'p':pwd})    #sql中加入key值，打印结果就会变成字典的格式而不是元组格式
result = cursor.fetchone()                  #取一行
cursor.close()
conn.close()
if result:
    print('登录成功')
else:
    print('登录失败')

print(result)

　　

import pymysql

# 增加，删，该
#增
# conn = pymysql.connect(host="localhost",user='root',password='',database="db3")
# cursor = conn.cursor()
# sql = "insert into userinfo(username,pwd) values('root','123123')"
# 受影响的行数
# r = cursor.execute(sql)
# #  ******
# conn.commit()     #对数据库有改变均要执行conn.commit()命令，提交给数据库。所以增删改均需有这条命令，查不需要。
# cursor.close()
# conn.close()

# conn = pymysql.connect(host="localhost",user='root',password='',database="db3")
# cursor = conn.cursor()
# # sql = "insert into userinfo(username,pwd) values(%s,%s)"
# # cursor.execute(sql,(user,pwd,))
#
# sql = "insert into userinfo(username,password) values(%s,%s)"
# # 受影响的行数
# r = cursor.executemany(sql,[('egon','sb'),('laoyao','BS')])
# #  ******
# conn.commit()
# cursor.close()
# conn.close()




# 查
# conn = pymysql.connect(host="localhost",user='root',password='',database="db666")
# cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
# sql = "select * from userinfo"
# cursor.execute(sql)

# cursor.scroll(1,mode='relative')  # 相对当前位置移动
# cursor.scroll(2,mode='absolute') # 相对绝对位置移动
# result = cursor.fetchone()
# print(result)
# result = cursor.fetchone()
# print(result)
# result = cursor.fetchone()
# print(result)
# result = cursor.fetchall()
# print(result)


# result = cursor.fetchmany(4)
# print(result)
# cursor.close()
# conn.close()




# 新插入数据的自增ID: cursor.lastrowid
# import pymysql
#
# conn = pymysql.connect(host="localhost",user='root',password='',database="db3")
# cursor = conn.cursor()
# sql = "insert into userinfo(username,pwd) values('asdfasdf','123123')"
# cursor.execute(sql)
# conn.commit()
# print(cursor.lastrowid)       #lastrowid最后一个自增id
# cursor.close()
# conn.close()

　　

6、作业

作业：
        参考表结构：
            用户类型

            用户信息

            权限

            用户类型&权限
        功能：

            # 登陆、注册、找回密码
            # 用户管理
            # 用户类型
            # 权限管理
            # 分配权限

        特别的：程序仅一个可执行文件

 

create database wuSir default character set utf8 collate utf8_general_ci;

use wuSir;


create table auth_info(
    aid int not null auto_increment primary key,
    auth_name varchar(32),
    unique(auth_name)
    )engine=innodb default charset=utf8;


create table user_info(
    uid int not null auto_increment primary key,
    name varchar(32),
    passwd varchar(32),
    sex ENUM("男","女")
    )engine=innodb default charset=utf8;

create table user_auth(
    id int,
    auth_id int,
    constraint auth_info foreign key(auth_id) references auth_info(aid),
    constraint user_info foreign key(id) references user_info(uid)
    )engine=innodb default charset=utf8;



insert into auth_info(auth_name) values("订单管理"),("用户管理"),("菜单管理"),("权限分配"),("Bug管理");

insert into user_info(name,passwd,sex) values("alex",123,"男"),("egon",123,"男");

insert into user_auth(id,auth_id) values(1,1),(2,1),(2,2),(2,3);

创建库表 SQL