Question

I have a file that corrals my re-usable functions into one file (functions.php). It’s include_once()‘d on every page that needs it. I’m getting an error when my custom functions are trying to access a MySQL connection outside their own scope. The source is a bit like this:

<?php
    // functions.php
    $connect = mysql_connect("localhost", "user", "pass") or die("MySQL said: ".mysql_error());
    mysql_select_db("database", $connect) or die("MySQL said: ".mysql_error()); // no error

    /* ... */

    function getmotd($user) {           
        $query = "SELECT cid FROM `users`
        WHERE id = ".$user;
        $query = mysql_query($query, $connect); // error occurs here, $connect is not a valid MySQL link-resource
        /* ... */
    }
?>

Why can’t my function access variables declared above it’s scope? I can get a successful connection by reproducing $connect‘s declaration within the function.

Any insight into how I can work around this or what I’m doing wrong here?

Answer 1

Use the global keyword.

Example

function getmotd($user) {  
     global $connect;
    $query = "SELECT cid FROM `users`
    WHERE id = ".$user;
    $query = mysql_query($query, $connect); // error occurs here, $connect is not a valid MySQL link-resource
    /* ... */
}

You can also do it like this

function getmotd($user) {  
    $query = "SELECT cid FROM `users`
    WHERE id = ".$user;
    $query = mysql_query($query, $GLOBALS['connect']); // error occurs here, $connect is not a valid MySQL link-resource
    /* ... */
}

If you want to make re-usable codes, you’d probably be better off with OOP. Create a class for the database, and add some properties for the database info, and access them from the functions by using the this keyword.