MySql和PHP错误登录记住系统

Question

I will create a Simple Login System and i need to remember the last 5 incorrect login in mysql, but how to create a update loop for 5 login? Ex: login incorrect 1:

$connection = mysqli_connect($host, $username, $password, $database) or die("Unable to connect to the MySQL Server!");
$sql_query = "INSERT INTO login(date,user,ip) VALUES('$today','$_POST['user']','$ip')"

Same code for login2, 3,4,5 but after 5 login how to update the first incorrect login? And for 6° incorrect login how to update the 2° incorrect login?

$sql_query = 'UPDATE login SET date="' . $date . etc etc; But

but how do I know the older incorrect login to update it?

Answer 1

I would use the modulo operation to get the correct index. The modulo operation gives you the remainder of the division operation. Assuming to start counting from 0, you need to perform INSERT in [0,1,2,3,4] and then start updating.

Assuming that the $attempt variable contains the amount of attempts you can retrieve the index by doing this:

$index = $attempt % 5

$index will then contain the correct login to update:

 5 % 5 = 0
 6 % 5 = 1
 7 % 5 = 2
 8 % 5 = 3
 9 % 5 = 4
10 % 5 = 0