三.实例演示insert/update/delect更新数据库

1.逻辑图

2.只是准备

3.代码展示

 1 import pymysql
 2 conn=pymysql.connect(
 3     host='192.168.199.249',
 4     port=3306,
 5     user='root',
 6     passwd='123456',
 7     db='imooc',
 8     charset='utf8'
 9 )
10 cursor=conn.cursor()
11 
12 sql_insert="insert into user(userid,username) values(10,'name10')"
13 sql_update="update user set username='name91' where userid=9"
14 sql_delete="delete from user where userid<3"
15 
16 cursor.execute(sql_insert)
17 print(cursor.rowcount)
18 cursor.execute(sql_update)
19 print(cursor.rowcount)
20 cursor.execute(sql_delete)
21 print(cursor.rowcount)
22 
23 conn.commit()
24 
25 cursor.close()
26 conn.close()

4.conn.rollback()代码展示

 1 import pymysql
 2 conn=pymysql.connect(
 3     host='192.168.199.249',
 4     port=3306,
 5     user='root',
 6     passwd='123456',
 7     db='imooc',
 8     charset='utf8'
 9 )
10 cursor=conn.cursor()
11 
12 sql_insert="insert into user(userid,username) values(10,'name10')"
13 sql_update="update user set username='name91' where userid=9"
14 sql_delete="delete from user where user<3"
15 
16 try:
17     cursor.execute(sql_insert)
18     print(cursor.rowcount)
19     cursor.execute(sql_update)
20     print(cursor.rowcount)
21     cursor.execute(sql_delete)
22     print(cursor.rowcount)
23 
24     conn.commit()
25 
26 except Exception as e:
27     print(e)
28     conn.rollback()
29 
30 cursor.close()
31 conn.close()