Python中怎样操作MySQL数据库,相信很多没有经验的人对此束手无策,为此本文总结了问题出现的原因和解决方法,通过这篇文章希望你能解决这个问题。
1. MySQL Connector
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)
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'))
username=1 OR 1=1 password=1 OR 1=1
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
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])
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()
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
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
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
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原文链接:https://my.oschina.net/u/4848094/blog/4746030