How can I make this log-in system un-exploitable

Question

I've made a python login system. But i think that this is easily exploitable. I don't really know php and mysql lot so I can't figure out how can I make it protected and server-sided.

Here's my code:

import time
import webbrowser
import os
import mysql.connector

conn = mysql.connector.connect(host="localhost", user="root", password="mysqldatabase", 
database="pazearn")

cursor=conn.cursor()
selectquery="select * from accounts"
cursor.execute(selectquery)
records=cursor.fetchall()



addur = 1
epc = 22

print("Welcome to Pazearn")
print("Login to your account\n")

username = input("Username: ")
password = input("Password: ")
money = 0
isval = False
for row in records:

    if row[0] == username and row[1] == password:
        isval = True
        money = row[2]
        break

if isval == False:

    print("[SYSTEM]: Invalid username or password, restart the program to re-enter.")
    time.sleep(10)
    quit()
else:

    os.system("cls")
    print("[SYSTEM]: Welcome back, " + username)
    print("[SYSTEM]: Booting system, please wait.")
    time.sleep(2)