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

 import pymysql
 conn=pymysql.connect(
     host='192.168.199.249',
     port=3306,
     user='root',
     passwd='',
     db='imooc',
     charset='utf8'
 )
 cursor=conn.cursor()

 sql_insert="insert into user(userid,username) values(10,'name10')"
 sql_update="update user set username='name91' where userid=9"
 sql_delete="delete from user where userid<3"

 cursor.execute(sql_insert)
 print(cursor.rowcount)
 cursor.execute(sql_update)
 print(cursor.rowcount)
 cursor.execute(sql_delete)
 print(cursor.rowcount)

 conn.commit()

 cursor.close()
 conn.close()

4.conn.rollback()代码展示

 import pymysql
 conn=pymysql.connect(
     host='192.168.199.249',
     port=3306,
     user='root',
     passwd='',
     db='imooc',
     charset='utf8'
 )
 cursor=conn.cursor()

 sql_insert="insert into user(userid,username) values(10,'name10')"
 sql_update="update user set username='name91' where userid=9"
 sql_delete="delete from user where user<3"

 try:
     cursor.execute(sql_insert)
     print(cursor.rowcount)
     cursor.execute(sql_update)
     print(cursor.rowcount)
     cursor.execute(sql_delete)
     print(cursor.rowcount)

     conn.commit()

 except Exception as e:
     print(e)
     conn.rollback()

 cursor.close()
 conn.close()