MySQL（10） - Python与MySQL的交互

1.MySQL驱动模块Connector的语法

1.1.下载驱动

进入官网下载对应版本驱动

---

1.2.创建连接

方式一：

import mysql.connector
con = mysql.connector.connect(
    host="localhost",port="3306",user="root",password="123456",database="vega"
)
con.close()

#运行脚本，不报错，连接成功

方式二：

import mysql.connector
config = {
    "host":"localhost",
    "port":3306,
    "user":"root",
    "password":"123456",
    "database":"vega"
}
con = mysql.connector.connect(**config)
#运行脚本，不报错，连接成功

---

1.3.创建游标

创建游标，执行SQL语句

 1 import mysql.connector
 2 #创建连接
 3 config = {
 4     "host":"localhost",
 5     "port":3306,
 6     "user":"root",
 7     "password":"123456",
 8     "database":"vega"
 9 }
10 con = mysql.connector.connect(**config)
11 #创建游标
12 cursor=con.cursor()
13 #编写sql
14 sql = "SELECT * FROM t_role;"
15 #通过游标执行sql
16 cursor.execute(sql)
17 #打印最后结果
18 for i in cursor:
19     print(i)
20     '''
21     输出结果
22     (2, '新闻编辑')
23     (1, '管理员')
24     '''
25 print(cursor,type(cursor))  #CMySQLCursor: SELECT * FROM t_role; <class 'mysql.connector.cursor_cext.CMySQLCursor'>

2.SQL注入攻击案例

 1 import mysql.connector
 2
 3 #创建连接
 4 config = {
 5     "host":"localhost",
 6     "port":3306,
 7     "user":"root",
 8     "password":"123456",
 9     "database":"vega"
10 }
11 con = mysql.connector.connect(**config)
12
13 #系统登录用户信息
14 username="1 OR 1=1"
15 password="1 OR 1=1"
16
17 #创建游标
18 cursor=con.cursor()
19 #编写sql
20 sql = "SELECT COUNT(*) FROM t_user WHERE username= %s" \
21       " AND AES_DECRYPT(UNHEX(password),'HelloWorld')=%s";
22 #通过游标执行sql
23 cursor.execute(sql%(username,password))
24 #打印最后结果
25 print(cursor.fetchone()[0]) #2
26 con.close()

 1 import mysql.connector
 2
 3 #创建连接
 4 config = {
 5     "host":"localhost",
 6     "port":3306,
 7     "user":"root",
 8     "password":"123456",
 9     "database":"vega"
10 }
11 con = mysql.connector.connect(**config)
12
13 #系统登录用户信息
14 username="1 OR 1=1"
15 password="1 OR 1=1"
16
17 #创建游标
18 cursor=con.cursor()
19 #编写sql
20 sql = "SELECT COUNT(*) FROM t_user WHERE username= %s" \
21       " AND AES_DECRYPT(UNHEX(password),'HelloWorld')=%s";
22 #通过游标执行sql
23 cursor.execute(sql,(username,password))
24 #打印最后结果
25 print(cursor.fetchone()[0]) #0
26 con.close()

3.MySQL Connector的异常处理

 1 import mysql.connector
 2
 3 try:
 4     con=mysql.connector.connect(
 5         host="localhost",
 6         port=3306,
 7         user="root",
 8         password="123456",
 9         database="vega"
10     )
11     con.start_transaction()
12     cursor = con.cursor()
13     sql="INSERT INTO t_type(type) VALUES(%s)"
14     cursor.execute(sql,("直播",))
15     con.commit()
16
17 except Exception as e:
18     if "con" in dir():
19         con.rollback()
20     print(e)
21 finally:
22     if "con" in dir():
23         con.close()

4.数据库连接池

 1 import mysql.connector.pooling
 2
 3 config={
 4     "host":"localhost",
 5     "port":3306,
 6     "user":"root",
 7     "password":"123456",
 8     "database":"vega"
 9 }
10 try:
11     pool=mysql.connector.pooling.MySQLConnectionPool(
12         **config,
13         pool_size=10
14     )
15     con=pool.get_connection()
16     con.start_transaction()
17     cursor=con.cursor()
18     sql="UPDATE t_type SET type=%s WHERE id=6"
19     cursor.execute(sql,("斗鱼",))
20     con.commit()
21 except Exception as e:
22     if "con" in dir():
23         con.rollback()
24     print(e)

 1 #  删除数据，delete和truncate
 2
 3 import mysql.connector.pooling
 4 config={
 5     "host":"localhost",
 6     "port":3306,
 7     "user":"root",
 8     "password":"123456",
 9     "database":"demo"
10 }
11 try:
12     pool=mysql.connector.pooling.MySQLConnectionPool(
13         **config,
14         pool_size=10
15     )
16     con=pool.get_connection()
17     # con.start_transaction()
18     cursor=con.cursor()
19     # sql="DELETE e,d FROM t_emp e JOIN t_dept d ON e.deptno=d.deptno " \
20     #     "WHERE d.deptno=20"
21     sql="TRUNCATE TABLE t_dept"     # TRUNCATE 实现删除功能
22     cursor.execute(sql)
23     # con.commit()
24 except Exception as e:
25     # if "con" in dir():
26     #     con.rollback()
27     print(e)

 1 #  使用 executemany()
 2
 3 import mysql.connector.pooling
 4
 5 config={
 6     "host":"localhost",
 7     "port":3306,
 8     "user":"root",
 9     "password":"123456",
10     "database":"demo"
11 }
12 try:
13     pool=mysql.connector.pooling.MySQLConnectionPool(
14         **config,
15         pool_size=10
16     )
17     con=pool.get_connection()
18     con.start_transaction()
19     cursor=con.cursor()
20     sql="INSERT INTO t_dept(deptno,dname,loc) VALUES(%s,%s,%s)"
21     data=[
22         [100,"A部门","北京"],[110,"B部门","上海"]
23     ]
24     cursor.executemany(sql,data)
25     con.commit()
26 except Exception as e:
27     if "con" in dir():
28         con.rollback()
29     print(e)

5.案例练习（一）

前置条件：数据库脚本

 1 SET NAMES utf8mb4;
 2 SET FOREIGN_KEY_CHECKS = 0;
 3
 4 -- ----------------------------
 5 -- Table structure for t_bonus
 6 -- ----------------------------
 7 DROP TABLE IF EXISTS `t_bonus`;
 8 CREATE TABLE `t_bonus` (
 9   `empno` int(4) NOT NULL,
10   `job` varchar(20) DEFAULT NULL,
11   `sal` decimal(10,2) DEFAULT NULL,
12   `comm` decimal(10,2) DEFAULT NULL,
13   PRIMARY KEY (`empno`)
14 ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
15
16 -- ----------------------------
17 -- Table structure for t_dept
18 -- ----------------------------
19 DROP TABLE IF EXISTS `t_dept`;
20 CREATE TABLE `t_dept` (
21   `deptno` int(2) NOT NULL,
22   `dname` varchar(20) DEFAULT NULL,
23   `loc` varchar(20) DEFAULT NULL,
24   PRIMARY KEY (`deptno`)
25 ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
26
27 -- ----------------------------
28 -- Records of t_dept
29 -- ----------------------------
30 BEGIN;
31 INSERT INTO `t_dept` VALUES (10, 'ACCOUNTING', 'NEW YORK');
32 INSERT INTO `t_dept` VALUES (20, 'RESEARCH', 'DALLAS');
33 INSERT INTO `t_dept` VALUES (30, 'SALES', 'CHICAGO');
34 INSERT INTO `t_dept` VALUES (40, 'OPERATIONS', 'BOSTON');
35 COMMIT;
36
37 -- ----------------------------
38 -- Table structure for t_emp
39 -- ----------------------------
40 DROP TABLE IF EXISTS `t_emp`;
41 CREATE TABLE `t_emp` (
42   `empno` int(4) NOT NULL,
43   `ename` varchar(20) DEFAULT NULL,
44   `job` varchar(20) DEFAULT NULL,
45   `mgr` int(4) DEFAULT NULL,
46   `hiredate` date DEFAULT NULL,
47   `sal` decimal(10,2) DEFAULT NULL,
48   `comm` decimal(10,2) DEFAULT NULL,
49   `deptno` int(2) DEFAULT NULL,
50   PRIMARY KEY (`empno`)
51 ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
52
53 -- ----------------------------
54 -- Records of t_emp
55 -- ----------------------------
56 BEGIN;
57 INSERT INTO `t_emp` VALUES (7369, 'SMITH', 'CLERK', 7902, '1980-12-17 00:00:00', 800.00, NULL, 20);
58 INSERT INTO `t_emp` VALUES (7499, 'ALLEN', 'SALESMAN', 7698, '1981-02-20 00:00:00', 1600.00, 300.00, 30);
59 INSERT INTO `t_emp` VALUES (7521, 'WARD', 'SALESMAN', 7698, '1981-02-22 00:00:00', 1250.00, 500.00, 30);
60 INSERT INTO `t_emp` VALUES (7566, 'JONES', 'MANAGER', 7839, '1981-04-02 00:00:00', 2975.00, NULL, 20);
61 INSERT INTO `t_emp` VALUES (7654, 'MARTIN', 'SALESMAN', 7698, '1981-09-28 00:00:00', 1250.00, 1400.00, 30);
62 INSERT INTO `t_emp` VALUES (7698, 'BLAKE', 'MANAGER', 7839, '1981-05-01 00:00:00', 2850.00, NULL, 30);
63 INSERT INTO `t_emp` VALUES (7782, 'CLARK', 'MANAGER', 7839, '1981-06-09 00:00:00', 2450.00, NULL, 10);
64 INSERT INTO `t_emp` VALUES (7788, 'SCOTT', 'ANALYST', 7566, '1982-12-09 00:00:00', 3000.00, NULL, 20);
65 INSERT INTO `t_emp` VALUES (7839, 'KING', 'PRESIDENT', NULL, '1981-11-17 00:00:00', 5000.00, NULL, 10);
66 INSERT INTO `t_emp` VALUES (7844, 'TURNER', 'SALESMAN', 7698, '1981-09-08 00:00:00', 1500.00, 0.00, 30);
67 INSERT INTO `t_emp` VALUES (7876, 'ADAMS', 'CLERK', 7788, '1983-01-12 00:00:00', 1100.00, NULL, 20);
68 INSERT INTO `t_emp` VALUES (7900, 'JAMES', 'CLERK', 7698, '1981-12-03 00:00:00', 950.00, NULL, 30);
69 INSERT INTO `t_emp` VALUES (7902, 'FORD', 'ANALYST', 7566, '1981-12-03 00:00:00', 3000.00, NULL, 20);
70 INSERT INTO `t_emp` VALUES (7934, 'MILLER', 'CLERK', 7782, '1982-01-23 00:00:00', 1300.00, NULL, 10);
71 COMMIT;
72
73 -- ----------------------------
74 -- Table structure for t_salgrade
75 -- ----------------------------
76 DROP TABLE IF EXISTS `t_salgrade`;
77 CREATE TABLE `t_salgrade` (
78   `grade` int(11) NOT NULL,
79   `losal` decimal(10,2) DEFAULT NULL,
80   `hisal` decimal(10,2) DEFAULT NULL,
81   PRIMARY KEY (`grade`)
82 ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
83
84 -- ----------------------------
85 -- Records of t_salgrade
86 -- ----------------------------
87 BEGIN;
88 INSERT INTO `t_salgrade` VALUES (1, 700.00, 1200.00);
89 INSERT INTO `t_salgrade` VALUES (2, 1201.00, 1400.00);
90 INSERT INTO `t_salgrade` VALUES (3, 1401.00, 2000.00);
91 INSERT INTO `t_salgrade` VALUES (4, 2001.00, 3000.00);
92 INSERT INTO `t_salgrade` VALUES (5, 3001.00, 9999.00);
93 COMMIT;
94
95 SET FOREIGN_KEY_CHECKS = 1;

 python代码

 1 import mysql.connector.pooling
 2
 3 config={
 4     "host":"localhost",
 5     "port":3306,
 6     "user":"root",
 7     "password":"123456",
 8     "database":"demo"
 9 }
10 try:
11     pool=mysql.connector.pooling.MySQLConnectionPool(
12         **config,
13         pool_size=10
14     )
15     con=pool.get_connection()
16     con.start_transaction()
17     cursor=con.cursor()
18     sql="DROP TABLE t_emp_new"
19     cursor.execute(sql)
20     sql = "CREATE TABLE t_emp_new LIKE t_emp"  #创建t_emp_new表，只将t_emp表的表结构同步到t_emp_new表中
21     # sql="CREATE TABLE t_emp_new AS (SELECT * FROM t_emp)"   创建t_emp_new表，将t_emp表的表结构和数据一起同步到t_emp_new表中
22     cursor.execute(sql)
23
24     #使用INSERT语句，把部门平均底薪超过公司平均底薪的这样部门里的
25     #员工信息导入到t_emp_new表里面，并且让这些员工隶属于sales部门
26     sql="SELECT AVG(sal) AS avg FROM t_emp"
27     cursor.execute(sql)
28     temp=cursor.fetchone()
29     avg=temp[0] #公司平均工资
30     sql="SELECT deptno FROM t_emp GROUP BY deptno HAVING AVG(sal)>=%s"
31     cursor.execute(sql,[avg])
32     temp=cursor.fetchall()
33     sql="INSERT INTO t_emp_new SELECT * FROM t_emp WHERE deptno IN ("
34     for index in range(len(temp)):
35         one = temp[index][0]
36         if index < len(temp)-1:
37             sql+=str(one)+","
38         else:
39             sql+=str(one)
40     sql+=")"
41     cursor.execute(sql)
42
43     sql = "DELETE FROM t_emp WHERE deptno IN ("
44     for index in range(len(temp)):
45         one = temp[index][0]
46         if index < len(temp) - 1:
47             sql += str(one) + ","
48         else:
49             sql += str(one)
50     sql += ")"
51     cursor.execute(sql)
52
53     sql = "SELECT deptno FROM t_dept WHERE dname=%s"
54     cursor.execute(sql, ["SALES"])
55     deptno = cursor.fetchone()[0]
56     sql = "UPDATE t_emp_new SET deptno=%s"
57     cursor.execute(sql, [deptno])
58     con.commit()
59 except Exception as e:
60     if "con" in dir():
61         con.close()
62     print(e)

6.案例练习（二）

 1 import mysql.connector.pooling
 2
 3 config={
 4     "host":"localhost",
 5     "port":3306,
 6     "user":"root",
 7     "password":"123456",
 8     "database":"demo"
 9 }
10 try:
11     pool=mysql.connector.pooling.MySQLConnectionPool(
12         **config,
13         pool_size=10
14     )
15     con=pool.get_connection()
16     con.start_transaction()
17     sql="INSERT INTO t_dept "\
18         "(SELECT MAX(deptno)+10,%s,%s FROM t_dept UNION "\
19         "SELECT MAX(deptno)+20,%s,%s FROM t_dept)"
20     cursor=con.cursor()
21     cursor.execute(sql,("A部门","北京","B部门","上海"))
22     con.commit()
23 except Exception as e:
24     if "con" in dir():
25         con.rollback()
26     print(e)

7.Python操作Mysql数据库的步骤

1.用什么方法创建Connection对象呢，常用参数有哪些？

• 直接在connect()函数里面加参数
  

  import mysql.connector
  
  con=mysql.connector.connect(
      host="localhost",
      port=3306,
      user="root",
      password="123456",
      database="vega"
  )

• 参数加在字典中，然后通过可变参数赋值
  

  import mysql.connector
  
  config = {
      "host":"localhost",
      "port":3306,
      "user":"root",
      "password":"123456",
      "database":"vega"
  }
  con = mysql.connector.connect(**config)

• 通过先建立连接池，再在连接池中获取连接
  

  import mysql.connector.pooling
  
  config={
      "host":"localhost",
      "port":3306,
      "user":"root",
      "password":"123456",
      "database":"demo"
  }
  pool=mysql.connector.pooling.MySQLConnectionPool(
      **config,
      pool_size=10
  )
  con=pool.get_connection()

2.Connection对象常用方法有哪些？

• 开启事务 con.start_transaction()

• 提交事务 con.commit()

• 回滚事务 con.rollback()

• 创建游标对象 cursor=con.cursor()

• 关闭连接 con.close()

3.Cursor对象常用的方法和属性是什么？

• 执行SQL语句 cursor.excute(sql,(参数,))
• 执行多次SQL cursor.executemany(sql,data) #data参数集合
• 返回一条执行结果 cursor.fetchone()
• 返回多条执行结果 cursor.fetchall()

4.使用事务有哪些方法？

• 开启事务 con.start_transaction()

• 提交事务 con.commit()

• 回滚事务 con.rollback()