How can I update mysql using python

I have a problem that my code did’t give me output, it’s connect Python to MySql without change the value I want to change, I have 2 scripts file one of them config have my host, password and user and another init

import mysql.connector
from config import USER, PASSWORD, HOST


class DbConnectionError(Exception):
    pass
# make a conniction to DB


def _connect_to_db(db_name):
    cnx = mysql.connector.connect(
        host=HOST,
        user=USER,
        password=PASSWORD,
        auth_plugin='mysql_native_password',
        database=db_name
    )

    return cnx


def change_maximum_mark():
    try:
        db_name = 'tests'
        db_connection = _connect_to_db(db_name)
        cur = db_connection.cursor()
        print(f'connected to database {db_name}')

        query = """
                UPDATE exams
                SET Max_mark = 100
                WHERE Exam_Name = 'Math' 
                """
        cur.execute(query)
        result = cur.fetchall()

        for i in result:
            print(i)

        cur.close()

    except Exception:
        raise DbConnectionError("Failed to read data from DB")

    finally:
        if db_connection:
            db_connection.close()
            print('DB conniction is closed')

I run these code to change value in mysql table, I success to connect Python and my sql but unfortunately the value not changed enter image description here