pymysql

一，IDE工具介绍
生产环境还是推荐使用mysql命令行，但为了方便我们测试，可以使用IDE工具
下载链接：https://pan.baidu.com/s/1bpo5mqj

掌握：
#1. 测试+链接数据库
#2. 新建库
#3. 新建表，新增字段+类型+约束
#4. 设计表：外键
#5. 新建查询
#6. 备份库/表

#注意：
批量加注释：ctrl+？键
批量去注释：ctrl+shift+？键

二，pymysql模块

先安装 pip3 install pymysql  才能导入这个模块

import pymysql

conn=pymysql.connect(
    host='127.0.0.1',
    port=3306,
    user='root',
    password='123',
    database='db42',
    charset='utf8'
)
cursor=conn.cursor(pymysql.cursors.DictCursor)
# rows=cursor.execute('show tables;')
rows=cursor.execute('select * from class;')
print(rows)
#
# print(cursor.fetchone())
# print(cursor.fetchmany(2))
# print(cursor.fetchone())
# print(cursor.fetchall())
#
# print(cursor.fetchall())
# cursor.scroll(3,'absolute')
# print(cursor.fetchone())
#
# print(cursor.fetchone())
# print(cursor.fetchone())
# cursor.scroll(1,'relative')
# print(cursor.fetchone())
#
# cursor.close()
# conn.close()

import pymysql #pip3 install pymysql

conn=pymysql.connect(
    host='127.0.0.1',
    port=3306,
    user='root',
    password='123',
    database='db42',
    charset='utf8'
)
cursor=conn.cursor(pymysql.cursors.DictCursor)


inp_user=input('用户名>>：').strip() #inp_user=""
inp_pwd=input('密码>>：').strip() #inp_pwd=""
sql="select * from user where name='%s' and password='%s'" %(inp_user,inp_pwd)
print(sql)


rows=cursor.execute(sql)
if rows:
    print('登录成功')
else:
    print('登录失败')

cursor.close()
conn.close()



直接改变了sql  绕过了密码和用户名

#在服务器端防止sql注入问题：不要自己拼接字符串，让pymysql模块去拼接
import pymysql #pip3 install pymysql

conn=pymysql.connect(
    host='127.0.0.1',
    port=3306,
    user='root',
    password='123',
    database='db42',
    charset='utf8'
)
cursor=conn.cursor(pymysql.cursors.DictCursor)


inp_user=input('用户名>>：').strip() #inp_user=""
inp_pwd=input('密码>>：').strip() #inp_pwd=""
sql="select * from user where name=%s and password=%s"
print(sql)


rows=cursor.execute(sql,(inp_user,inp_pwd))
if rows:
    print('登录成功')
else:
    print('登录失败')

cursor.close()
conn.close()

三，、增、删、改：conn.commit()

import pymysql #pip3 install pymysql

conn=pymysql.connect(
    host='127.0.0.1',
    port=3306,
    user='root',
    password='123',
    database='db42',
    charset='utf8'
)
cursor=conn.cursor(pymysql.cursors.DictCursor)

# sql='insert into user(username,password) values(%s,%s)'
# rows=cursor.execute(sql,('EGON','123456'))
# print(rows)
# print(cursor.lastrowid)

# rows=cursor.execute('update user set username="alexSB" where id=2')
# print(rows)

# 一次插入多行记录
sql='insert into user(username,password) values(%s,%s)'
rows=cursor.executemany(sql,[('lwz','123'),('evia','455'),('lsd','333')])
print(rows)
print(cursor.lastrowid)

conn.commit() # 只有commit提交才会完成真正的修改
cursor.close()
conn.close()

四，查：fetchone，fetchmany，fetchall

fetchone（查询单条）
 fetchmany（查询多条）
 fetchall（查询所有）

import pymysql

conn=pymysql.connect(
    host='127.0.0.1',
    port=3306,
    user='root',
    password='123',
    database='db42',
    charset='utf8'
)
cursor=conn.cursor(pymysql.cursors.DictCursor)
# rows=cursor.execute('show tables;')
rows=cursor.execute('select * from class;')
print(rows)
#
# print(cursor.fetchone())
# print(cursor.fetchmany(2))
# print(cursor.fetchone())
# print(cursor.fetchall())
#
# print(cursor.fetchall())
# cursor.scroll(3,'absolute')
# print(cursor.fetchone())
#
# print(cursor.fetchone())
# print(cursor.fetchone())
# cursor.scroll(1,'relative')
# print(cursor.fetchone())
#
# cursor.close()
# conn.close()

五，获取最后

------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()