I have some PHP login system errors...

So, I have successfully connected to my database and I can use the table 'users' to log in. But when I add a user to the table looking like this:

ID:1 Username: Something password: somespwd

So that look ok right? But it only seems to use the password of the first table. So say I added another user like this:

ID:1 / Username: Something / password: somepswd

ID:2 / Username: Somethingelse / password: otherpswd

Then if I try to log in I can go:

username(input): something

password(input): somepswd

then it works.

Then if I go:

username(input): Somethingelse

password(input): otherpswd

it doesen't work because the I have to use the first password (somepswd) to get logged in.

So that was my main issue, bu then I thought about the fact that I could use WHATEVER username I want right? So I tryed it and the reuslt was that I logged in kind of like this:

username(input):notevenindb

password(input):somepswd

IT WORKS because it has the password of the first password in the table.

here is the code, I hope you take the time to look at this. thank you <3

code:

<?php session_start(); if(isset($_POST['login'])) { include_once("db.php"); $username = strip_tags($_POST['username']); $password = strip_tags($_POST['password']);

    $username = stripslashes($username);
    $password = stripslashes($password);

    $username = mysqli_real_escape_string($conn, $username);
    $password = mysqli_real_escape_string($conn, $password);

    $password = md5($password);

    $sql = "SELECT * FROM  `users`";
    $query = mysqli_query($conn, $sql);
    $row = mysqli_fetch_array($query);
    $id = $row['id'];
    $db_password = $row['password'];

    if($password == $db_password) {
        $_SESSION['username'] = $username;
        $_SESSION['id'] = $id;
        header("location: loggedin.php");
    } else {
        echo "You didn't enter the correct details!";
    }
}

?>