Can someone tell me why this code seems to work but doesn't... please?

Question

when I run this code I get no errors and everything seems to work but it doesn't actually write to the database. If I copy the sql string that is generated by the print function and paste it directly into a MariaDB terminal session, it works perfectly. This is the sql that is generated:

INSERT INTO msg_store (cons, prod, file) VALUES ('XXX','YYY','ZZZ');

If I change the database name or any of the required parameters, I get errors as expected. I have successfully used most of this code in other applications. I'm running it on a Raspberry Pi 4 with Python3.7

import pymysql

class C_DataBase: # Database Communication Class
    def __init__(self, host_ip, db_name, user_name, password, poll_time = None):
        self.ip = host_ip
        self.db = db_name
        self.un = user_name
        self.pw = password
        if poll_time is not None:
            self.pt = poll_time

def connect(db):
    try:
        con = pymysql.connect(host=db.ip,  # host
                             user=db.un,  # username
                             passwd=db.pw,  # password
                             db=db.db)  # name of the data base
        return con.cursor()  # Open the database and return

    except Exception as e:
       print('DBOpenError, Failed to Connect to={}, IP={}, user={}, pw={}'.format(db.db, db.ip, db.un, db.pw))

def pub_sql(db, cons, prod, msgb):
    con = connect(db)
    col = "cons, prod, file"
    val ="'" + cons + "','" + prod + "','" +  msgb + "'"

    sql = "INSERT INTO msg_store (" + col + ") VALUES (" + val + ");"
    try:
        rslt = con.execute(sql)
        print(rslt, sql)
        con.close()
    except Exception as e:
        print('SQLWriteError={}'.format(e))


if __name__ == '__main__':
    db = C_DataBase('localhost', 'testdb', 'rpi', 'rpi') # Create and populate a database object
    pub_sql(db, 'XXX', 'YYY', 'AAA') # Call the publishing function

mariaDB terminal session

;MariaDB [testdb]> INSERT INTO msg_store (cons, prod, file) VALUES ('XXX','YYY','AAA');

Query OK, 1 row affected (33.852 sec)

MariaDB [testdb]>
MariaDB [testdb]> select * from testdb.msg_store;
+------+------+---------+
| cons | prod | file    |
+------+------+---------+
| ABC  | DEF  | message |
| ABC  | DEF  | message |
| XXX  | DEF  | message |
| XXX  | YYY  | ZZZ     |
| XXX  | YYY  | AAA     |
+------+------+---------+
5 rows in set (0.001 sec)

Run status screen from Pycharm

Answer 1

After con.execute() you should also do con.commit() after that you can close the connection