mysql之pymysql模块

一、pymysql的基本使用

import pymysql

user = input('user>>>:').strip()
pwd = input('password>>>:').strip()

# 建立连接
conn = pymysql.connect(
    host='127.0.0.1',
    port=3306,
    user='root',
    password='112233',
    db='db8',
    charset='utf8'
)

# 拿到游标

cursor = conn.cursor()

# 执行sql语句

sql = 'select * from userinfo where user = "%s" and pwd="%s"' % (user, pwd)

rows = cursor.execute(sql)

cursor.close()
conn.close()

# 进行判断
if rows:
    print('登陆成功')
else:
    print('登陆失败')

二、解决sql注入问题

import pymysql

user = input('user>>>:').strip()
pwd = input('password>>>:').strip()

# 建立连接
conn = pymysql.connect(
    host='127.0.0.1',
    port=3306,
    user='root',
    password='112233',
    db='db8',
    charset='utf8'
)

# 拿到游标

cursor = conn.cursor()

# 执行sql语句

# sql = 'select * from userinfo where user = "%s" and pwd="%s"' % (user, pwd)
# print(sql)
'''
方式一
# select * from userinfo where user = "egon" -- xxxxxx" and pwd=""
# 在sql中 --之后的都代表注释掉。所以等于只查 where user ="egon"

方式二
# select * from userinfo where user = "xxx" or 1=1 -- hahahaha" and pwd=""
# select * from userinfo where user = "xxx" or 1=1 其实是执行了这个,1=1永远成立
'''

# 防止sql注入的方法,过滤到非法操作

sql = 'select * from userinfo where user = %s and pwd= %s '
rows = cursor.execute(sql, (user, pwd))  # 将用户密码在这里传入，pymysql内置的功能就能帮助你过滤

cursor.close()
conn.close()

# 进行判断
if rows:
    print('登陆成功')
else:
    print('登陆失败')

三、pymysql之增删改查

# 1、增删改
import pymysql

# 建立链接
conn = pymysql.connect(
    host='127.0.0.1',
    port=3306,
    user='root',
    password='112233',
    db='db8',
    charset='utf8'
)
# 拿游标
cursor = conn.cursor()

# 执行sql
# 增、删、改
sql = 'insert userinfo(user,pwd) values(%s,%s)'  # 删改把insert换成相应的关键字就行
# cursor.execute(sql,('wxx','123'))

# rows = cursor.executemany(sql, [('yxx', '123'), ('egon1', '123'), ('egon2', '123')])  # 插入多条记录
# print(rows) # 3

rows = cursor.executemany(sql,[('egon3','123'),('egon4','123'),('egon5','123')])
print(cursor.lastrowid)  # 7 插入之前id走到哪了，在插入三条就是7、8、9

conn.commit()  # 执行commit才会对数据库进行操作

# 关闭游标和链接
cursor.close()
conn.close()


# 2、查询

import pymysql

# 建立链接
conn = pymysql.connect(
    host='127.0.0.1',
    port=3306,
    user='root',
    password='112233',
    db='db8',
    charset='utf8'
)
# 拿游标
cursor = conn.cursor(pymysql.cursors.DictCursor)  # 以字典的形式取出来

# 执行sql
# 查询
rows = cursor.execute('select * from userinfo;')
# print(rows)  6

# print(cursor.fetchone())  # 取一行,直到取到没有就显示None
# print(cursor.fetchone())
# print(cursor.fetchmany(5))  # 指定取几行

# print(cursor.fetchall())  # 取全部


# cursor.scroll(3,'absolute') # 绝对位置
# print(cursor.fetchone())  # 第四条

print(cursor.fetchone())
cursor.scroll(2,mode='relative')  # 基于当前的位置往后在跳两个
print(cursor.fetchone()) # 4 ，如果用absolute就是3


# 关闭游标和链接
cursor.close()
conn.close()