PHP OOP function won't grab data unless another function is called

I'm having this weird problem right now, I'm just working on a small admin backend thing that will allow users to upload a file and download it again, simple stuff.

I'm using PHP OOP with Classes and functions and things. Still pretty new at it. Currently on one page I have a "getRecentLinks" function that will call information from a couple tables and put it all out on the page in a table, it works just fine. One of the options on this page is to download the file that was uploaded to that individual row. So I just want it to be a link you click on to say, file-download.php?id=3.

Now on file-download.php I'm currently just testing to get the information on the page before I add the headers and things in there. So I just have a simple

$l = new Links();
$file = $l->getFileInfo($_GET['id']);
print_r($file);

this SHOULD just return information from the d开发者_运维问答atabase, id, name of file, size, data, and mimetype.

Now this doesn't work. I have no idea why but it doesn't.

Now on my page where I have the getRecentLinks() function it works just fine. I even brought in the getRecentLinks() into my file-download.php page so it's setup like this.

$l = new Links();
$l->getRecentLinks();
$file = $l->getFileInfo($_GET['id']);
print_r($file);

This works just fine and dandy, The second I remove getRecentLinks() it stops calling information from getFileInfo() and I cannot figure it out. I mean it's not a huge deal i could just keep #l->getRecentLinks() there but I can see this getting annoying if I have to add it to every page I want to do something, I'm just at the start of this project.

Here's the code in the Links class

public function getFileInfo($id)
{
    $result = $this->runQuery("SELECT * FROM file WHERE id ='".mysql_real_escape_string($id)."'");

    $resultSet = $this->fetch($result);

    return $resultSet;
}

and

public function getRecentLinks()
{
    $result = $this->runQuery("SELECT * FROM links ORDER BY date DESC");

    while($j = $this->fetch($result))
    {
        $resultSet[] = $j;
    }

    return $resultSet;
}

And heres my connections and fetch functions a friend helped me develop

public function runQuery($sql) {
    $this->connection = mysql_connect($this->dbhost, $this->dbuser, $this->dbpass);
    if(!$this->connection) {
        die("MySQL is down.");
    } else {
        mysql_select_db($this->dbname);
    }
    $result = mysql_query($sql,$this->connection) or die(mysql_error());

    return $result;
}

public function fetch($result)
{
    $resultSet = mysql_fetch_assoc($result);

    return $resultSet;
}

mysql_real_escape_string requires a connection. Since getRecentLinks opens a connection it works. But you call mysql_real_escape_string before runQuery (in execution order) in getFileInfo. In this case, I assume the id is an integer, so you're better off and a lot cheaper to call intval($_GET['id']).