Python操作MySQL数据库的示例代码
时间：2020-11-29 10:27:00|栏目：Python代码|点击： 次
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
- 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）
1.4 事务管理和异常处理
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
- 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
栏 目：Python代码
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