section_4.python操作mysqlsql注入导入导出数据库

一、python操作 mysql

# pip install pymysql

1、基本语法

# (1) 创建连接  host  user  password  database 这四个参数必须写
conn = pymysql.connect(host="127.0.0.1",user="root",password="123456",database="db0826",charset="utf8",port=3306)
# (2) 创建游标对象(该对象可以操作数据库增删改查)
cursor = conn.cursor()
print(cursor)
# (3) 执行sql语句
sql = "select * from employee"
# 返回的是数据的总条数
res = cursor.execute(sql)
print(res)
# (4)获取数据 fetchone 获取一条
res = cursor.fetchone()
res = cursor.fetchone()
print(res)
# (5) 释放游标对象
cursor.close()
# (6) 关闭连接
conn.close()

2、创建删除 表

2.1、创建一张表

conn = pymysql.connect(host="127.0.0.1",user="root",password="123456",database="db0826")
cursor = conn.cursor()

# 1.创建一张表
sql = """
create table t1(
id int unsigned primary key auto_increment,
first_name char(10) not null,
last_name char(10) not null,
age int unsigned,
sex tinyint,
money float
)
"""

res = cursor.execute(sql)
print(res)

2.2、查看表结构

sql = "desc t1"
res = cursor.execute(sql)
print(res) # 6条字段数据
print(cursor.fetchone())
print(cursor.fetchone())
print(cursor.fetchone())
print(cursor.fetchone())
print(cursor.fetchone())
print(cursor.fetchone())

2.3、删除表

try:
    sql = "drop table t1"
    res = cursor.execute(sql)
    print(res)
except:
    pass

cursor.close()
conn.close()

3、事务处理

"""
pymysql 操作事务处理时,需要commit提交数据,才会变化,否则rollback回滚.恢复到最初状态
"""

conn = pymysql.connect(host="127.0.0.1",user="root",password="123456",database="db0826")
cursor = conn.cursor()
sql1 = "begin"
sql2 = "update employee set emp_name = '123egon' where id = 1"
sql3 = "commit"
res1 = cursor.execute(sql1)
res2 = cursor.execute(sql2)
res3 = cursor.execute(sql3)
# print(res1,res2,res3) # 返回值没有意义
# fetchone 与查询sql有关 , 增删改无效;
# tup = cursor.fetchone()
# print(tup)

cursor.close()
conn.close()

 二、python操作mysql 增删改查

"""
    python 操作mysql时,默认开启事务,必须在增删改之后
    提交数据,才会真正对数据库发生变化,默认默认是回滚
    
    提交数据: conn.commit()
    回滚数据: conn.rollback()
    
    execute      一次插入一条
    executemany  一次插入多条

"""

# 1.创建mysql 链接
conn = pymysql.connect(host="127.0.0.1",user="root",password="123456",database="db0826")
# 查询数据,默认是元组,可以设置返回的类型为字典 pymysql.cursors.DictCursor
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor) # cursor=pymysql.cursors.DictCursor

1、增

sql = "insert into t1(first_name,last_name,age,sex,money) values(%s,%s,%s,%s,%s)"

# 一次插入一条
res = cursor.execute(sql, ("宋","云杰",30,0,15000) )
print(res) # 1
# 获取最后插入这条数据的id号(针对单条数据插入)
print(cursor.lastrowid) # 3

res = cursor.executemany(  sql,  [  ("高","云峰",50,1,16000) , ("戈","隆",80,1,17000) , ("袁","伟倬",120,0,130000) , ("刘","欣慰",150,0,18000)   ]   )
print(res) # 插入的条数
# 针对于多条数据,搜最后的id 可以通过倒序查询id
sql = "select id from t1 order by id desc limit 1"
res = cursor.execute(sql)
print(res)
# 获取最后一个id号
res = cursor.fetchone()
print(res)

2、删

sql = "delete from t1 where id = %s"
res = cursor.execute(sql , (3,))
print(res)
if res:    
    print("删除成功")
else:
    print("删除失败")

3、改

sql = "update t1 set first_name = %s where id = %s"
res = cursor.execute(sql,("王",4))
print(res)

if res:
    print("修改成功")
else:
    print("修改失败")

4、查

"""
fetchone  fetchmany fetchall 都是基于上一条数据往下查询.
"""

sql = "select * from t1"
res = cursor.execute(sql)
print(res) # 总条数

4.1、获取一条数据 fetchone

# {'id': 4, 'first_name': '王', 'last_name': '云杰', 'age': 30, 'sex': 0, 'money': 15000.0}
res = cursor.fetchone()
print(res)

4.2、获取多条数据 fetchmany

data = cursor.fetchmany() # 默认搜索的的是一条数据
print(data)
data = cursor.fetchmany(3)
print(data) 

for row in data :
    # print(row)
    first_name = row["first_name"]
    last_name = row["last_name"]
    age = row["age"]
    if row["sex"] == 0:
        sex = "女性"
    else:
        sex = "男性"
    
    money = row["money"]
    print("姓:{},名:{},年龄:{},姓名:{},收入:{}".format(first_name,last_name,age,sex,money)  )

4.3、获取所有数据 fetchall

data = cursor.fetchall()
print(data)

4.4、自定义搜索查询的位置

4.4.1、相对滚动

sql = "select * from t1 where id >= 20"
res = cursor.execute(sql)
print(res)

# 1.相对滚动 (正数相对于当前位置往后滚,负数反之.)
cursor.scroll(3,mode="relative")
res = cursor.fetchone()
print(res)

cursor.scroll(3,mode="relative")
res = cursor.fetchone()
print(res)

# 2 往前滚
cursor.scroll(-2,mode="relative")
res = cursor.fetchone()
print(res)

4.4.2、绝对滚动

cursor.scroll(0,mode="absolute")
print(cursor.fetchone())

cursor.scroll(1,mode="absolute")
print(cursor.fetchone())

cursor.scroll(3,mode="absolute")
print(cursor.fetchone())

# 往前滚没有数据,超出范围error
"""
cursor.scroll(-1,mode="absolute")
print(cursor.fetchone())

4.4.3、提交数据

# 在进行增删改查时,必须提交数据,才会产生影响.
conn.commit()
cursor.close()
conn.close()

三、sql注入攻击

创建表：

create table usr_pwd(
id int unsigned primary key auto_increment,
username varchar(255) not null,
password varchar(255) not null
)

1、sql注入的现象

import pymysql
user = input("请输入用户名: >>> ").strip()
pwd = input("请输入密码: >>> ").strip()

conn = pymysql.connect(host="127.0.0.1",user="root",password="123456",database="db0826")
cursor = conn.cursor()

sql = "select * from usr_pwd where username='%s' and password='%s' " % (user,pwd)
print(sql)
res = cursor.execute(sql)
print(res) # 查询的条数

if res:
    print("登录成功")
else:
    print("登陆失败")


cursor.close()
conn.close()

运行：

"""
输入: sfsdf' or 3=3 -- sdfsd
# -- 后面的字符串都会被注释掉, 前面账号虽然是错的 但是 2=2是真的 绕开了账号和密码的判断;
select * from usr_pwd where username='afasdfasdfasdf' or 2=2 -- sfasdf' and password='3434
"""

2、使用预处理，提前对sql语句中的特殊符号进行处理

"""
使用预处理机制,可以避免绝大多数sql注入的问题
execute 如果参数为2个,将默认开启预处理
execute(sql , (参数1,参数2,参数3 .... ) )
"""

import pymysql
user = input("请输入用户名: >>> ").strip()
pwd = input("请输入密码: >>> ").strip()


conn = pymysql.connect(host="127.0.0.1",user="root",password="123456",database="db0826")
cursor = conn.cursor()
sql = "select * from usr_pwd where username=%s and password=%s"
res = cursor.execute(sql, (user,pwd) )


print("登陆成功" if res  else "登录失败")

cursor.close()
conn.close()

四、导入导出数据库

1、导出数据库

"""
第一步: 先退出数据库
第二部: 切换到对应的路径
mysqldump -uroot -p db0824 > db0824.sql
第三部:
    # 导出所有内容
    mysqldump -uroot -p db0824 > db0824.sql
    # 导出单个表
    mysqldump -uroot -p db0824 t1 > t1.sql
"""

2、导入数据库

"""
第一步 : 先创建一个空的数据库
第二部 : 找到sql对应文件目录
第三部 : source 路径/文件
    use 数据库
    source D:db0824.sql
"""