MySQL之pymysql模块

目录

• pymysql
  • • • 连接mysql
    • sql注入攻击
    • 解决方法：
    • pymysql增删改查
      • • pymysql默认开启了事务
        • pymysql 不开启事务
      • 增删改

pymysql

连接mysql

import pymysql
mysql_addres = {
"host": "localhost",
 "user": "root",
 "password": "123456",
 "charset": "utf8"
}

conn = pymysql.connect(**mysql_addres)		# 连接数据库

status = conn.server_status		# 判断数据库连接是否异常。

if status:
	print("连接数据库异常！")
	return status

cursor = con.cursor(pymysql.cursors.DictCursor)	# pymysql.cursors.DictCursor 返回数据为({},{},{},)。好处在于返回的结果带数据类型
use_database = "use day40_3_zuoye"
sql1 = "select * from course"
cursor.execute(use_database)		# 执行sql
cursor.execute(sql1)				# 执行sql

res = cursor.fetchall()		# 查询结果
res1 = cursor.fetchall()	# 游标已经到最后了，此时取结果是取不到的。需要移动游标
cursor.scroll(-1,mode="relative") # mode：relative或者absolute ,relative相对路径，从游标的位置进行移动，单位为负数。absolute绝对路径从最开始的地方进行偏移，单位为正数。

sql注入攻击

sql注入指的是,用户在输入数据时,按照sql的语法,来编写带有攻击目的的sql语句,并插入到原始语句中执行.

例如:登录功能,需要用户输入用户名和密码

import pymysql
try:
	mysql_addres = {
        "host": "localhost",
         "user": "root",
         "password": "123456",
         "charset": "utf8"
    }

    conn = pymysql.connect(**mysql_addres)		# 连接数据库

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

    count = cursor.execute("select *from user where name = '%s' and password = '%s'" % (user,password))
    if count:
            print("登录成功!")
        else:
            print("登录失败!")
except Exception as e:
    print(type(e),e)
finally:
    if cursor:cursor.close()
    if conn: conn.close()

上述代码有被注入攻击的危险

尝试在用户名中输入一下内容，密码随意

尝试在用户名中输入以下内容,密码随意
 jerry' — ass 
或者连用户名都不用写
' or 1 = 1 -- asaa

解决方法：

1. 客户端在发送sql给服务器前进行re判断

   这样的问题在于一些程序可以模拟客户端直接发送请求给服务器

2. 在服务器端将sql交给mysql是作进一步处理,相关的代码其实pymysql已经做了封装

   我们只要保证不要自己来拼接sql语句即可,将拼接参数操作交给pymysql.

import pymysql
try:
    conn = pymysql.connect(host="127.0.0.1",port=3306,user="root",password="",db="day46",)
    print("连接服务器成功!")
    cursor = conn.cursor(pymysql.cursors.DictCursor)
    
    user = input("username:")
    password = input("password:")

    sql = "select *from user where name = %s and password = %s"
    print(sql)
    count = cursor.execute(sql,(user,password)) # 参数交给模块
    if count:
        print("登录成功!")
    else:
        print("登录失败!")
except Exception as e:
    print(type(e),e)
finally:
    if cursor:cursor.close()
    if conn: conn.close()

pymysql增删改查

pymysql默认开启了事务

# 开启了事务
def test():
        mysql_addres = {
        "host": "localhost",
        "user": "root",
        "password": "123456",
        "charset": "utf8",
        "db":"test",
        "autocommit":False      # 默认为False
    }
    con = pymysql.connect(**mysql_addres)
    cursor = con.cursor(pymysql.cursors.DictCursor)
    
    # 转账业务,张三需要跟李四转账500块钱。
    sql1 = "update plf set money = money - 500 where name = %s"
    cursor.execute(sql1,("张三",))
    sql2 = "update plf set money = money + 500 where name = %s"
    cursor.execute(sql2, ("李四",))
    con.commit()

    cursor.close()
    con.close()
test()

pymysql 不开启事务

def test_one():
    mysql_addres = {
        "host": "localhost",
        "user": "root",
        "password": "123456",
        "charset": "utf8",
        "db":"test",
        "autocommit":True      # 默认为False
    }
    con = pymysql.connect(**mysql_addres)

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

    try:
        # 转账业务,张三需要跟李四转账500块钱。
        cursor.execute("start transaction")
        sql1 = "update plf set money = money - 500 where name = %s"
        cursor.execute(sql1,("张三",))
        sql2 = "update plf set money = money + 500 where name = %s"        
        cursor.execute(sql2, ("李四",))
        cursor.execute("commit")
        cursor.close()
        con.close()
    except Exception as e:
        con.rollback()
        
test_one()

增删改

import pymysql


# 1.建立连接
try:
    conn = pymysql.connect(host="127.0.0.1",port=3306,user="root",password="",db="day46",)
    print("连接服务器成功!")
    cursor = conn.cursor(pymysql.cursors.DictCursor)
    
    #增
    #sql = "insert into user values(null,%s,%s,%s)"
    #count = cursor.execute(sql,("tom","man","123321"))
    # 一次性插入多条记录
    #sql = "insert into user values (null,%s,%s,%s)"
    #count = cursor.executemany(sql, [("周芷若","woman","123"), ("赵敏","woman","321")])
    
    #删
    # count = cursor.execute("delete from user where id = 1")

    
    #改
    count = cursor.execute("update user set name = '刘大炮' where id = 1")

    if count:
        print("执行成功!")
    else:
        print("执行失败!")

    # 获取最新的id
    # print(cursor.lastrowid)
except Exception as e:
    print(type(e),e)

finally:
    if cursor:cursor.close()
    if conn: conn.close()