pymysql模块

#安装
pip3 install pymysql

import pymysql
user=input('用户名: ').strip()
pwd=input('密码: ').strip()

#链接
conn=pymysql.connect(host='localhost',user='root',password='123',database='egon',charset='utf8) #指定字符编码，可显示中文
#游标
cursor=conn.cursor()

#执行sql语句
sql='select * from userinfo where name="%s" and password="%s"' %(user,pwd) #注意%s需要加引号
print(sql)
res=cursor.execute(sql) #执行sql语句，返回sql查询成功的记录数目
print(res)

cursor.close()
conn.close()

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

最后那一个空格，在一条sql语句中如果遇到select * from t1 where id > 3 -- and name='egon';则--之后的条件被注释掉了

#1、sql注入之：用户存在，绕过密码
egon' -- 任意字符

#2、sql注入之：用户不存在，绕过用户与密码
xxx' or 1=1 -- 任意字符

# 原来是我们对sql进行字符串拼接
# sql="select * from userinfo where name='%s' and password='%s'" %(user,pwd)
# print(sql)
# res=cursor.execute(sql)

#改写为（execute帮我们做字符串拼接，我们无需且一定不能再为%s加引号了）
sql="select * from userinfo where name=%s and password=%s" #！！！注意%s需要去掉引号，因为pymysql会自动为我们加上

单条数据执行sql语句
cursor.execute(sql,[user,pwd]) #pymysql模块自动帮我们解决sql注入的问题，只要我们按照pymysql的规矩来。

import pymysql
#链接
conn=pymysql.connect(host='localhost',user='root',password='123',database='egon')
#游标
cursor=conn.cursor()

#执行sql语句
#part1
# sql='insert into userinfo(name,password) values("root","123456");'
# res=cursor.execute(sql) #执行sql语句，返回sql影响成功的行数
# print(res)

#part2
# sql='insert into userinfo(name,password) values(%s,%s);'
# res=cursor.execute(sql,("root","123456")) #执行sql语句，返回sql影响成功的行数
# print(res)

#part3
sql='insert into userinfo(name,password) values(%s,%s);'
res=cursor.executemany(sql,[("root","123456"),("lhf","12356"),("eee","156")]) #执行sql语句，返回sql影响成功的行数
print(res)

conn.commit() #提交后才发现表中插入记录成功
cursor.close()
conn.close()

import pymysql
#链接
conn=pymysql.connect(host='localhost',user='root',password='123',database='egon',charset='utf8')
#游标
cursor=conn.cursor()

import pymysql
conn=pymysql.connect(host='localhost',user='root',password='123',database='egon',charset='utf8)
cursor=conn.cursor()

sql='insert into userinfo(name,password) values("xxx","123");'
rows=cursor.execute(sql)

conn.commit()
print(cursor.lastrowid) #在commit之前和之后都可以查看
cursor.close()
conn.close()

import pymysql

class SQLHelper(object):

    def __init__(self):
        self.conn = None
        self.cursor = None

    def open(self,cursor=pymysql.cursors.DictCursor):
        self.conn = db_pool.POOL.connection()
        self.cursor = self.conn.cursor(cursor=cursor)

    def close(self):
        self.cursor.close()
        self.conn.close()

    def fetchone(self,sql,params):
        cursor = self.cursor
        cursor.execute(sql,params)
        result = cursor.fetchone()

        return result

    def fetchall(self, sql, params):
        cursor = self.cursor
        cursor.execute(sql, params)
        result = cursor.fetchall()
        return result

    def create(self, sql, params):
        cursor = self.cursor
        cursor.execute(sql, params)
        self.conn.commit()
        return self.cursor.lastrowid

    def delete(self, sql, params):
        cursor = self.cursor
        cursor.execute(sql, params)
        self.conn.commit()

    def update(self, sql, params):
        cursor = self.cursor
        cursor.execute(sql, params)
        self.conn.commit()

    def __enter__(self):
        self.open()
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        self.close()

        with SQLHelper() as helper:
            result1 = helper.fetchone('select * from users where name=%s and pwd = %s',['hc',123,])   # 查单条记录
    
            result2 = helper.fetchall('select * from users ',[])  #查所有记录
        
            helper.create('insert into user (name,pwd) value(%s,%s)',['hc',123])    # 创建记录