PHP + MySQL problems :(

Question

I am havin trouble with this code:

if ($_GET['offline']) {$extranet = $_GET['offline'];} else {$extranet = $online;}
$sql = mysqli_query($db,"UPDATE tbl_system SET value = '$extranet' WHERE property = 'extranet'");
echo $_GET['offline'];
echo $extranet;
echo $online;

In the database, the value of the field where the property = extranet is 1. Results of echo:

$_GET['offline'] = 0 
$extranet        = 1
$online          = 1

Now, obviously, something's wrong here.

The URL to give this GET is: ?app=admincp&offline=0, so $_GET['offline'] is not the problem.

The problem must lie in the if statement, but I can't figure it out,

Any ideas?

Is there code that actually sets the value of extranet? I would rewrite this to be more clear. Make sure you initialize your variables properly, print them out in one nice string before any conditions and a similar string after all is done and update the post. Then we will be more able to help you. Jacob — TheJacobTaylor
– TheJacobTaylor, Commented Aug 17, 2009 at 21:44
If I am reading this right, offline is set to 0, extranet is set to the value of $online which starts at 1 — TheJacobTaylor
– TheJacobTaylor, Commented Aug 17, 2009 at 21:46
yep, I add that (sanitation) once i can guarantee that the raw code is working :) ty Koning baard, @ TJT, yep :) — bear
– bear, Commented Aug 17, 2009 at 21:54

Federico klez Culloca · Accepted Answer · 2009-08-17 21:41:32Z

2

$_GET['offline'] is 0, and 0 evaluates to false, so the statement goes right. if you want to check whether offline is passed as an argument you have to use isset()

if (!isset($_GET['offline'])) {$extranet = $_GET['offline'];} else {$extranet = $online;}

answered Aug 17, 2009 at 21:41

Federico klez Culloca

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Ryan · Accepted Answer · 2009-08-17 21:44:13Z

2

Yikes! In addition to karim's comment- sanitize your inputs! You're taking a URL parameter and putting it directly into an SQL query. A url of

?app=admincp&offline=';DROP table tbl_system;--

Would ruin you!

answered Aug 17, 2009 at 21:44

Ryan

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1 Comment

bear Over a year ago

yep, I add that once i can guarantee that the raw code is working :)

karim79 · Accepted Answer · 2009-08-20 02:59:20Z

2

if ($_GET['offline'])

That will return false because the string "0" evaluates to false in PHP, so the if statement's condition can never evaluate to true. Use isset or array_key_exists instead. e.g.:

if (isset($_GET['offline'])) { ... }

or:

if (array_key_exists('offline',$_GET)) { ... }

In your case, you'll want to know whether or not the value is exactly the string zero "0". I would recommend using strcmp:

if (strcmp($_GET['offline'],"0") === 0) {
    $extranet = $_GET['offline'];
} else {
    $extranet = $online;
}
$sql = mysqli_query($db,"UPDATE tbl_system SET value = '$extranet' WHERE property = 'extranet'");
echo $_GET['offline'];
echo $extranet;
echo $online;

edited Aug 20, 2009 at 2:59

answered Aug 17, 2009 at 21:39

karim79

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Comments

benjy · Accepted Answer · 2009-08-17 21:41:14Z

1

$_GET['offline'] is zero in the URL you provide, so if($_GET['offline']) and everything in that block will never be hit. Use isset() instead.

answered Aug 17, 2009 at 21:41

benjy

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Comments

b82 · Accepted Answer · 2009-08-20 03:05:48Z

1

if (strcmp($_GET['offline'],"0") === 0) {
    $extranet = $_GET['offline'];
} else {
    $extranet = $online;
}

This will throw an error in the case that $_GET['offline'] is not set, better to use !isset($_GET['offline'])

answered Aug 20, 2009 at 3:05

b82

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