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Python操作MySQL数据库详解

时间:2020-07-13 15:25:07      阅读:74      评论:0      收藏:0      [点我收藏+]

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前言

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技术图片

 

1. MySQL Connector

1.1 创建连接

 import mysql.connector
 config={
     "host":"localhost","port":"3306",
     "user":"root","password":"password",
     "database":"demo"
 }
 con=mysql.connector.connect(**config)
 import mysql.connector
 config={
     "host":"localhost","port":"3306",
     "user":"root","password":"password",
     "database":"demo"
 }
 con=mysql.connector.connect(**config)

 

1.2 Cursor

 import mysql.connector
 con=mysql.connector.connect(
     host="localhost",port="3306",
     user="root",password="password",
     database="demo"
 )
 cursor=con.cursor()
 sql="SELECT empno,job,sal FROM t_bonus;"
 cursor.execute(sql)
 print(type(cursor))
 for i in cursor:
     print(i)
 con.close()
 
 Result:
     <class mysql.connector.cursor_cext.CMySQLCursor>
     (7369, CLERK, Decimal(8000.00))
     (7499, SALESMAN, Decimal(1600.00))
     (7521, SALESMAN, Decimal(1250.00))
     (7566, MANAGER, Decimal(2975.00))
     (7654, SALESMAN, Decimal(1250.00))
     (7698, MANAGER, Decimal(2850.00))
     (7782, MANAGER, Decimal(2450.00))
     (7788, ANALYST, Decimal(3000.00))
     (7839, PRESIDENT, Decimal(5000.00))
     (7844, SALESMAN, Decimal(1500.00))
     (7900, CLERK, Decimal(950.00))
     (7902, ANALYST, Decimal(3000.00))
     (7934, CLERK, Decimal(1300.00))

 

1.3 SQL注入攻击

  1. username=1 OR 1=1 password=1 OR 1=1
  2. 在使用字符串直接拼接时OR之前不管对错,与OR结合都为true
  3. 解决方法——预编译(也可以提高速度)
username="1 OR 1=1"
 password="1 OR 1=1"
 sql="SELECT COUNT(*) FROM t_user WHERE username=%s AND AES_DECRYPT(UNHEX(password),‘helloWorld‘)=%s"
 cursor.execute(sql,(username,password))
 print(cursor.fetchone()[0])

 

1.4 事务管理和异常处理

  1. sql连接和使用异常处理异常
 import mysql.connector
 try:
     con=mysql.connector.connect(
         host="localhost",port="3306",
         user="root",password="password",
         database="demo"
     )
     con.start_transaction()
     cursor=con.cursor()
     sql="INSERT INTO t_dept(deptno,dname,loc) VALUES(%s,%s,%s);"
     cursor.execute(sql,(60,"SALES","HUBAI"))
     con.commit()
 except Exception as e:
     if "con" in dir():
         con.rollback()
     print(e)
 finally:
     if "con" in dir():
         con.close()

 

1.5 删除数据

import mysql.connector,mysql.connector.pooling
 config={
     "host": "localhost", "port": "3306",
     "user": "root", "password": "password",
     "database": "demo"
 }
 try:
     pool=mysql.connector.pooling.MySQLConnectionPool(**config,pool_size=5)
     con=pool.get_connection()
     con.start_transaction()
     cursor = con.cursor()
     sql = "DELETE FROM t_dept WHERE deptno=%s"
     cursor.execute(sql, (70,))
     con.commit()
 except Exception as e:
     if "con" in dir():
         con.rollback()
     print(e)
 # do not need to close con

 

executemany() 反复执行一条SQL语句

 import mysql.connector,mysql.connector.pooling
 config={
     "host": "localhost", "port": "3306",
     "user": "root", "password": "password",
     "database": "demo"
 }
 try:
     pool=mysql.connector.pooling.MySQLConnectionPool(**config,pool_size=5)
     con=pool.get_connection()
     con.start_transaction()
     cursor = con.cursor()
     sql = "INSERT INTO t_dept(deptno,dname,loc) VALUES(%s,%s,%s);"
     date=[[70,"SALES","BEIJING"],[80,"ACTOR","SHANGHAI"]]
     cursor.executemany(sql, date)
     con.commit()
 except Exception as e:
     if "con" in dir():
         con.rollback()
     print(e)
 # do not need to close con

 

2. 数据库连接池

  1. 数据库的连接是昂贵的,一个连接要经过TCP三次握手,四次挥手,而且一台计算机的最大线程数也是有限的
  2. 数据库连接池技术就是先创建好连接,再直接拿出来使用
import mysql.connector,mysql.connector.pooling
 config={
     "host": "localhost", "port": "3306",
     "user": "root", "password": "password",
     "database": "demo"
 }
 try:
     pool=mysql.connector.pooling.MySQLConnectionPool(**config,pool_size=5)
     con=pool.get_connection()
     con.start_transaction()
     cursor = con.cursor()
     sql = "INSERT INTO t_dept(deptno,dname,loc) VALUES(%s,%s,%s);"
     cursor.execute(sql, (70, "SALES", "HUBAI"))
     con.commit()
 except Exception as e:
     if "con" in dir():
         con.rollback()
     print(e)
 # do not need to close con

 

Python操作MySQL数据库详解

标签:tab   type   not   tran   manager   nec   nal   操作   into   

原文地址:https://www.cnblogs.com/zwhy8/p/13293335.html

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