How can developers handle scenarios where multiple users in a MySQL database have the same combination of username and password in a PHP login script?

When multiple users in a MySQL database have the same combination of username and password, developers can handle this scenario by adding an additional unique identifier, such as a user ID, to differentiate between the users. This unique identifier can be used in the login script to ensure that the correct user is authenticated. 

// Assuming $username and $password are retrieved from the login form
$query = "SELECT * FROM users WHERE username = '$username' AND password = '$password'";
$result = mysqli_query($connection, $query);

if(mysqli_num_rows($result) == 1){
    $row = mysqli_fetch_assoc($result);
    $user_id = $row['user_id']; // Assuming 'user_id' is the unique identifier in the database
    // Proceed with authentication
} else {
    // Handle incorrect login credentials
}

Keywords

MySQL PHP login script duplicate usernames password hashing

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