PHP: include a file from separate folder
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![enter image description here][1]

I am new to PHP, attached image shows the location of files it will help you to give answer. I want to include  `'db/functions.php'` in my file `'process/delete.php'` but nothing is working.
I have tried following at start of `'delete.php'`

    include_once '/db/functions.php';
    include_once './db/functions.php';
    include_once '../db/functions.php';
    include_once $_SERVER['DOCUMENT_ROOT'].'/db/functions.php';

When I open MAMP/log/php_error.log file it shows following error

    [28-Jul-2012 21:55:23] PHP Warning:  include_once() 
    [<a href='function.include'>function.include</a>]: 
    Failed opening '/db/functions.php' for inclusion 
    (include_path='.:/Applications/MAMP/bin/php/php5.3.6/lib/php') in 
    /Applications/MAMP/htdocs/electromart/process/delete.php on line 3

Where line 3 is include statement.


  [1]: http://i.stack.imgur.com/7QxQS.png