标签:delete userinfo 日期 let har 排序 tab 必须 ati
就是利用mysql 语法 使其 查询条件永远为真
import pymysql
conn = pymysql.connect(host='127.0.0.1', user='root', password="123",
database='day43')
cur = conn.cursor()
user = "akhksh' or 1=1 ;-- "
password = '*******'
sql = "select * from userinfo where username = %s and password =%s;"
print(sql)
cur.execute(sql,(user,password))
ret = cur.fetchone()
print(ret)
cur.close()
conn.close()
# 光标会记录位置 取得那就会记录此时的位置
import pymysql
conn = pymysql.connect(
host='127.0.0.1',
port=3306,
user='root',
password='',
database='daycs',
charset='utf8',
)
cursor = conn.cursor(pymysql.cursors.DictCursor)
sql = "select * from book;"
ret = cursor.execute(sql)#ret 受影响的行数
print(ret)
cursor.scroll(1,'absolute') #绝对移动,按照数据最开始位置往下移动1条
print(cursor.fetchmany()) #取出多条 默认取出1条
# print(cursor.fetchone()) #取出单条
# print(cursor.fetchall()) #取出所有的
cursor.scroll(3,'absolute') #绝对移动,按照数据最开始位置往下移动3条
cursor.scroll(3,'relative') #相对移动,按照当前光标位置往下移动3条
cursor.close()#关闭游标
conn.close()#关闭连接
# 光标会记录位置 取得那就会记录此时的位置
import pymysql
conn = pymysql.connect(
host='127.0.0.1',
port=3306,
user='root',
password='',
database='daycs',
charset='utf8',
)
cursor = conn.cursor(pymysql.cursors.DictCursor)
sql = "insert into book values(%s,'eg','知识没有用出版社',200,'2047-7-5');"
ret = cursor.execute(sql,('独孤九'))
print(ret)
conn.commit()# 增删改都必须进行提交操作(commit)
文件内容
倚天屠龙记 egon 北京工业地雷出版社 70 20190701
九阳神功 alex 人民音乐不好听出版社 5 20180704
九阴真经 yuan 北京工业地雷出版社 62 20170712
九阴白骨爪 jinxin 人民音乐不好听出版社 40 20190807
独孤九剑 alex 北京工业地雷出版社 12 20170901
降龙十巴掌 egon 知识产权没有用出版社 20 20190705
葵花宝典 yuan 知识产权没有用出版社 33 20190802
学python从开始到放弃|alex|人民大学出版社|50|20180701
学mysql从开始到放弃|egon|机械工业出版社|60|20180603
学html从开始到放弃|alex|机械工业出版社|20|20180401
学css从开始到放弃|wusir|机械工业出版社|120|20180502
学js从开始到放弃|wusir|机械工业出版社|100|20180730
利用python操作
#第一步手动创建表
# create table book(
# id int primary key auto_increment,
# book_name char(20) not null,
# author char(12) not null,
# press char(20) not null,
# price float(6,2),
# pub_date date
# );
# 写入数据
import pymysql
conn = pymysql.Connection(host='127.0.0.1', user='root', password="",
database='daycs')
cur = conn.cursor()#右边
with open('book.txt',encoding='utf-8') as f:
try:
for line in f:
line = line.strip()
if '\t' in line:
lst = line.split('\t')
elif '|' in line:
lst = line.split('|')
sql = 'insert into book(book_name,author,press,price,pub_date) values (%s,%s,%s,%s,%s);'
cur.execute(sql,lst)
except Exception:
conn.rollback()#操作不成功 回滚
conn.commit()
cur.close()
conn.close()
# select book_name,price from book where author = 'egon'
# 2.找出最贵的图书的价格
# select max(price) from book;
# select price,book_name from book order by price desc limit 1;
# 3.求所有图书的均价
# select avg(price) from book;
# 4.将所有图书按照出版日期排序
# select * from book order by pub_date;
# 5.查询alex写的所有书的平均价格
# select avg(price) from book where author = 'alex'
# 扩展: 求所有人自己出版的图书的平均价格
# select author,avg(price) from book group by author
# 扩展: 求所有人自己出版的图书的平均价格>30的所有人
# select author from book group by author having avg(price)>30
# 6.查询人民音乐不好听出版社出版的所有图书
# select * from book where press = '人民音乐不好听出版社';
# 7.查询人民音乐出版社出版的alex写的所有图书和价格
# select * from book where press = '人民音乐不好听出版社' and author = 'alex';
# 8.找出出版图书均价最高的作者
# select author,avg(price) as avg_p from book group by author order by avg_p desc limit 1;
# 9.找出最新出版的图书的作者和出版社
# select author,press from book order by pub_date desc limit 1;
# 10.显示各出版社出版的所有图书
# select press,group_concat(book_name) from book group by press;
# 11.查找价格最高的图书,并将它的价格修改为50元
# select max(price) from book;
# update book set price = 50 where price = 70
# 12.删除价格最低的那本书对应的数据
# select min(price) from book;
# delete from book where price = 5;
# 13.将所有alex写的书作者修改成alexsb
# update book set author = 'alexsb' where author = 'alex';
# 14.select year(publish_date) from book
# 自己研究上面sql语句中的year函数的功能,完成需求:
# 将所有2017年出版的图书从数据库中删除
# delete from book where year(publish_date) = 2017;
标签:delete userinfo 日期 let har 排序 tab 必须 ati
原文地址:https://www.cnblogs.com/saoqiang/p/11456251.html