Quote:
Undefined index, error in my SQL?
We can't do much more than guessing with what you gave us.
If problem is in PHP, typically,
username
does not exist in
$_SESSION
$username = $_SESSION['username'];
Use the debugger to get position of error and to look at the contain of variables.
If problem is in SQL, you need to check if
username
is a field of database. Are you sure about the {} around the username ?
$query = "SELECT * FROM userspiders WHERE username = '{$username}'";
-----
Not necessary a solution to your question, but another problem you have.
Never build an SQL query by concatenating strings. Sooner or later, you will do it with user inputs, and this opens door to a vulnerability named "SQL injection", it is dangerous for your database and error prone.
A single quote in a name and your program crash. If a user input a name like "Brian O'Conner" can crash your app, it is an SQL injection vulnerability, and the crash is the least of the problems, a malicious user input and it is promoted to SQL commands with all credentials.
SQL injection - Wikipedia[
^]
SQL Injection[
^]
SQL Injection Attacks by Example[
^]
PHP: SQL Injection - Manual[
^]
SQL Injection Prevention Cheat Sheet - OWASP[
^]
How can I explain SQL injection without technical jargon? - Information Security Stack Exchange[
^]
-----
Your code do not behave the way you expect, or you don't understand why !
There is an almost universal solution: Run your code on debugger step by step, inspect variables.
The debugger is here to show you what your code is doing and your task is to compare with what it should do.
There is no magic in the debugger, it don't know what your code is supposed to do, it don't find bugs, it just help you to by showing you what is going on. When the code don't do what is expected, you are close to a bug.
To see what your code is doing: Just set a breakpoint and see your code performing, the debugger allow you to execute lines 1 by 1 and to inspect variables as it execute.
phpdbg | php debugger[
^]
Debugging techniques for PHP programmers[
^]
The debugger is here to only show you what your code is doing and your task is to compare with what it should do.