Hello,

I thought I would experiment some mysql I just learnt by making a little php page called 'getoil.php'. I have a database with an id, username, password and an oil column. All this code does is it updates a user's amount of oil (as if they're purchasing it - i took this idea from a game), the problem is, it only updates one of the user's oil, the one i've speciifed as 'ahmed'. What i want to know is, how can i specify it to update the amount of oil for the user that submitted it. In other words, if user ahmed submits the form, only his oil amount gets updated, same for user fred, george...etc.

I attempted doing this by using require_once('myloginpage.php'); and then doing mysql_query("SELECT * FROM users WHERE username='$user'") but all that did was attempt to log me in

Here's the code I'm using:

<?php
require_once('global.php'); // session start
require_once('security.php'); // restrict access to logged users
require_once('conn.php'); // db connection

$result = mysql_query("SELECT * FROM users WHERE username='ahmed'") or die(mysql_error());  
$row = mysql_fetch_array($result); // gets the data from username ahmed - i want this to be for whatever username is signed in

$oldoil = $row['oil']; // the originally amount of oil they had

$oil = $_POST['oil']; // the oil they're buying
$newoil = $oil+$oldoil; // the oil they're going to have in total
$sql = "UPDATE users SET oil = $newoil WHERE username='ahmed'";
mysql_query($sql)or die(mysql_error()); 
echo "You now have ".$newoil." barrels after purchasing ".$oil;

?>

This post has been edited by Sayid Ahmed: 24 Aug, 2008 - 02:24 PM

When the user logs in, you can set a session variable to the username they used. That or after you authenticate them, pull the username from their record and store it in the $_SESSION variable. Then whenever you need access to the user's name, you can use this variable in the query.


Lets say after they logged in and you verified who they were, you would set $_SESSION['user'] to their username they used during login.

Then on this page you can access it like so...

// Get the session variable and put it in a variable called $user
$user = $_SESSION["user"];

$result = mysql_query("SELECT * FROM users WHERE username='$user'") or die(mysql_error());  
$row = mysql_fetch_array($result); // gets the data from username ahmed - i want this to be for whatever username is signed in

$oldoil = $row['oil']; // the originally amount of oil they had

$oil = $_POST['oil']; // the oil they're buying
$newoil = $oil+$oldoil; // the oil they're going to have in total
$sql = "UPDATE users SET oil = $newoil WHERE username='$user'";
mysql_query($sql)or die(mysql_error()); 
echo "You now have ".$newoil." barrels after purchasing ".$oil;

See how we pulled out their username from the session, stored it in $user and then used $user in the two queries?

Hope that helps you out.

"At DIC we be pulling usernames from sessions type of code ninjas...we also pull teeth, hair, and sometimes on rare occasions fingers."

I completely understood that but unfortunately it didn't work. I attempted it again by adding $user = $_SESSION["user"]; to several different pages (login page, login success page) and echoing it but it was blank

Hi Sayid,

Martyr2s example should work. I've broken it down into a few steps to help try to clear anything up.

Firstly make sure session_start() is at the top of each page - with this on, it will allow you to store and move 'session' data.

Secondly, where you have on the login page something like:

in your if condition (if a user is found - i think you have a header('Location:blahblah... in there at the mo) you put this line before the header location:


Then, on any page on the site, echo $_SESSION['username']; will show you the username.

Let us know if you're still stuck.

woops i didnt put the $_POST['uname_txt'] part in, and i did it after the header(), it works now

Thanks to both of you

EDIT: Randomly im getting

What's this about?

This post has been edited by Sayid Ahmed: 25 Aug, 2008 - 07:50 AM

as I posted before in my giant list of common php problems, headers and sessions need to start BEFORE anything is echo'd on the page... so move session_start() up to the top of the page