Database connection variable not being found only on one page

Question

The connection file is:

$DBconnect = mysqli_connect("localhost", "root", "", "project" );

And this works on all pages except one, which is giving this error: Undefined variable: DBconnect

for this part:

include_once('connection.php');
// Function that will convert a user id into their username
function getusername($uid) {

$res = mysqli_query($DBconnect, "SELECT username FROM users WHERE id='".$uid."' LIMIT 1") or die(mysql_error());

Thanks for advice

You define the variable in the global scope, but try to access it in function scope. That does not work. Try this inside the function: `$_GLOBALS['DBconnect']` — arkascha, Sep 23 '15 at 10:46
Read up about variable scope. But for a quick fix, include the line `global $DBconnect;` in the function. — Geoff Atkins, Sep 23 '15 at 10:47
1. Make sure that this is the correct path to connection.php. 2. It is defined in your global and not the needed(function) scope. — Konstantin Rachev, Sep 23 '15 at 10:48
Ah yes thanks trying to use the global variable in the function was the problem — zigg76, Sep 23 '15 at 10:53

score 0 · Answer 1 · answered Sep 23 '15 at 10:50

Change this

    function getusername($uid){
$res = mysqli_query($DBconnect, "SELECT username FROM users WHERE id='".$uid."' LIMIT 1") or die(mysql_error());
}

to this

    function getusername($uid){
    global $DBconnect;
    $res = mysqli_query($DBconnect, "SELECT username FROM users WHERE id='".$uid."' LIMIT 1") or die(mysql_error());
    }

or

function getusername($uid,$DBconnect){
        $res = mysqli_query($DBconnect, "SELECT username FROM users WHERE id='".$uid."' LIMIT 1") or die(mysql_error());
        }

RiggsFolly · Answer 2 · 2015-09-23T10:58:26.283

This is a scope issue.

$DBConnect is available in the Global scope, but you cannot get access to the global scope in a function automatically. So pass the $DBConnect as a parameter to the function and all is well.

include_once('connection.php');

function getusername($uid, $DBConnect) {

    $res = mysqli_query($DBconnect, "SELECT username 
                                     FROM users 
                                     WHERE id='$uid' LIMIT 1"); 
    if ( ! $res ) {
       echo mysql_error();
       exit;
    }

}

// call function with an extra parameter i.e. the $DBConnect

getusername($uid, $DBConnect);

Database connection variable not being found only on one page

2 Answers2