PHP - Undefined variable

Question

I\'m doing some exercises from Beginners PHP & MySQL by Mr. Tucker.

On his example everything works fine, but on my PC there is an error:

Answer 1

Just before while where you set variable $passwordRetrieved declare it so it should look like this:

$tUser_SQLselect_Query = mysql_query($tUser_SQLselect);
$passwordRetrieved = "";


while ($row = mysql_fetch_array($tUser_SQLselect_Query, MYSQL_ASSOC)) {
    $passwordRetrieved = $row['password'];
}

Answer 2

As this question has already been answered, I would also add instead of using mysql_fetch_array with the MYSQL_ASSOC parameter, you can just use mysql_fetch_assoc() :)

Answer 3

If your query returned no results, then $passwordRetrieved is undefined (just like the message says).

You should throw an error when you couldn't find any users with username=$username (which is also an invalid login).