Script Won't Write Updates to Database

Question

I cannot get the following code to write to the database even though I get no errors when it runs. If the value of playCount is NULL and the value of lastPLayed is not NULL then I want to write the value of lastPlayed to NULL.

#!/usr/bin/env python3

import sqlite3


try:
    conn = sqlite3.connect("/home/mp/Desktop/MyVideos116.db")
    conn.row_factory = sqlite3.Row
    cursor = conn.cursor()
    
    print("connected to database successfully")

    query = "SELECT * from files"
    playCount = cursor.execute(query).fetchall()
        
    for i in playCount:

        if (i["playCount"]) == None and (i["lastPlayed"] != None):

            update = "UPDATE files SET playCount = ? WHERE lastPlayed = ?"

            data = (None, None)

            cursor.execute(update, data)

            print (i["playCount"], i["lastPlayed"])
    
            conn.commit()

    # Closing the connection
    conn.close()

except:
    print("database error")