pip3 install pymysql

import pymysql
user= input('用户名：>>').strip()
pwd= input('密码：>>').strip()# 先链接，拿到游标
conn=pymysql.connect(host='localhost',user='root',password='123456',database='day47',charset='utf8')
cursor=conn.cursor() 　　# 拿到游标，即mysql >
# 执行sql
sql='select * from user where user="%s" and password="%s";'%(user,pwd)
print(sql)　　 # 注意%s需要加双引号
rows = cursor.execute(sql) 　　 # 拿到受影响的行数

cursor.close()
conn.close()if rows: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)
# rows=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
rows=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
先链接，拿到游标
conn=pymysql.connect(host='localhost',user='root',password='123456',database='day47')
cursor=conn.cursor() #拿到游标，即mysql >
#执行sql   增：
sql='insert into user1(user,password) VALUES (%s,%s)'
print(sql)
# rows = cursor.execute(sql,('xixi',123))  #插入一条记录
rows = cursor.executemany(sql,[('xixi',123),('aaa',456),('ttt',147)]) #插入多行记录
print('%s row in set (0.00 sec)'%rows)conn.commit() #提交到数据库
cursor.close()
conn.close()

# coding:utf-8
import pymysql# 打开数据库连接
db = pymysql.connect(host='localhost', port=3306,user='username', passwd='password', db='database_name', charset='utf8')# 使用cursor()方法获取操作游标
cursor = db.cursor()# SQL 插入语句
sql = "INSERT INTO EMPLOYEE(FIRST_NAME, AGE, SEX) VALUES (%s,%s,%s)"
# 一个tuple或者list
T = (('xiaoming', 31, 'boy'), ('hong', 22, 'girl'), ('wang', 90, 'man'))try:# 执行sql语句
    cursor.executemany(sql, T)# 提交到数据库执行
    db.commit()
except :# 如果发生错误则回滚
    db.rollback()
# 关闭游标
cursor.close()
# 关闭数据库连接
db.close()

import pymysql
#先链接，拿到游标
name=input('>>').strip()
conn=pymysql.connect(host='localhost',user='root',password='123456',database='day47')
cursor=conn.cursor() #拿到游标，即mysql >
#执行sql   删：
sql='delete from user1 where user =%s;'  #删除数据
print(sql)
rows = cursor.execute(sql,(name))
print('%s row in set (0.00 sec)'%rows)conn.commit() #提交到数据库
cursor.close()
conn.close()

import pymysql
#先链接，拿到游标
id=input('>>').strip()
conn=pymysql.connect(host='localhost',user='root',password='123456',database='day47')
cursor=conn.cursor() #拿到游标，即mysql >
#执行sql   改：
sql=' update user1 set password = "5555555" where id=%s;'
print(sql)
rows = cursor.execute(sql,(id))
print('%s row in set (0.00 sec)'%rows)conn.commit() #提交到数据库
cursor.close()
conn.close()

# ---------查fetchone,fetchmany,fetchall-----------
import pymysql
conn=pymysql.connect(host='localhost',user='root',password='123456',database='day47')
cursor=conn.cursor() #拿到游标，即mysql >
#执行sql   查：
sql='select * from user1;'
rows = cursor.execute(sql)#查单条fetchone
res1=cursor.fetchone()
res2=cursor.fetchone()
res3=cursor.fetchone()
print(res1)
print(res2)
print(res3)
print(res3[0])#查多条fetchmany
print(cursor.fetchmany(3))
print(cursor.fetchone())#查所有fetchall
print(cursor.fetchall())
print(cursor.fetchone())#-------光标的移动--------
#1.绝对路径：从文件的开头位置算起
print(cursor.fetchall())
cursor.scroll(1,mode='absolute')
print(cursor.fetchone())
cursor.scroll(3,mode='absolute')
print(cursor.fetchone())#2.相对路径：
print(cursor.fetchone())
print(cursor.fetchone())
cursor.scroll(2,mode='relative') #相对于上面的两条向后移两条
print(cursor.fetchone())print('%s row in set (0.00 sec)' %rows)
cursor.close()
conn.close()

------查看表中最后一行的iD
import pymysql
conn=pymysql.connect(host='localhost',user='root',password='123456',database='day47',charset='utf8')
cursor=conn.cursor()sql='insert into user1(user,password) values(%s,%s);'
rows=cursor.execute(sql,('alex','123'))
# rows=cursor.executemany(sql,[('yuanhao','123'),('laowu','123'),('kgf','12323')])
conn.commit()
print(cursor.lastrowid)  #查看表中最后一行的iD

cursor.close()
conn.close()

# 用twisted库将数据进行异步插入到数据库import pymysql
from twisted.enterprise import adbapi
from twisted.internet import reactorclass MysqlTwistedPipeline(object):def __init__(self, dbpool):self.dbpool = dbpool@classmethoddef from_settings(cls, settings):# 需要在setting中设置数据库配置参数dbparms = dict(host=settings['MYSQL_HOST'],db=settings['MYSQL_DBNAME'],user=settings['MYSQL_USER'],passwd=settings['MYSQL_PASSWORD'],charset='utf8',cursorclass=pymysql.cursors.DictCursor,use_unicode=True,)# 连接ConnectionPool（使用MySQLdb连接，或者pymysql）dbpool = adbapi.ConnectionPool("MySQLdb", **dbparms)  # **让参数变成可变化参数return cls(dbpool)  # 返回实例化对象def process_item(self, item, spider):# 使用twisted将MySQL插入变成异步执行query = self.dbpool.runInteraction(self.do_insert, item)# 添加异常处理
        query.addCallback(self.handle_error)def handle_error(self, failure):# 处理异步插入时的异常print(failure)def do_insert(self, cursor, item):# 执行具体的插入insert_sql = """insert into jobbole_artitle(name, base_url, date, comment)VALUES (%s, %s, %s, %s)"""cursor.execute(insert_sql, (item['name'], item['base_url'], item['date'], item['coment'],))