<?php 
    $test = array(); 
    $test[0]['name'] = 'zoe'; 
    $test[0]['email'] = 'lala@example.com'; 
    $test[0]['phone'] = '123-123-1234'; 
    $test[0]['trick'] = 'mezopia'; 


    $test[1]['name'] = 'Amanda'; 
    $test[1]['email'] = 'hot@example.com'; 
    $test[1]['phone'] = '123-123-1235'; 
    $test[1]['trick'] = 'youarecool'; 


    $test[2]['name'] = 'john'; 
    $test[2]['email'] = 'wowee@example.com'; 
    $test[2]['phone'] = '123-123-3333'; 
    $test[2]['trick'] = 'goneinanhour'; 


    print_r(columnSort($test, 'name')); 


    function columnSort($unsorted, $column) { 
        $sorted = $unsorted; 
        for ($i=0; $i < sizeof($sorted)-1; $i++) { 
          for ($j=0; $j<sizeof($sorted)-1-$i; $j++) 
            if ($sorted[$j][$column] > $sorted[$j+1][$column]) { 
              $tmp = $sorted[$j]; 
              $sorted[$j] = $sorted[$j+1]; 
              $sorted[$j+1] = $tmp; 
          } 
        } 
        return $sorted; 
    } 
    ?>

trovato su php.net

Spero possa servire ad altri!

A buon rendere

[PHP]
$a = array(
array(8,'',10),
array(19,'',30),
array(20,'',40)
);

function cmp($a, $b){
if($a[2] == $b[2])
return false;
return ($a[2] < $b[2]) ? -1 : 1;
}

usort($a,"cmp");

print_r($a);
[/PHP]