<?php

$data = array(
    array('name' => 'Alan',             'last' => 'Turing'  ),
    array('name' => 'Albert',           'last' => 'Einstein'),
    array('name' => 'Hans Albert',      'last' => 'Einstein'),
    array('name' => 'Lieserl Einstein', 'last' => 'Einstein'),
    array('name' => 'Mileva',           'last' => 'Einstein')
);

echo 'Before';
echo PHP_EOL;
echo PHP_EOL;

var_dump($data);



function sort_some_people($a, $b)
{
	$compareValue = 10 * strcmp($a['last'], $b['last']);
	$compareValue += 1 * strcmp($a['name'], $b['name']);
	return $compareValue;
}

usort($data, 'sort_some_people');

echo PHP_EOL;
echo 'After';
echo PHP_EOL;
echo PHP_EOL;

var_dump($data);

?>

Before

array(5) {
  [0]=>
  array(2) {
    ["name"]=>
    string(4) "Alan"
    ["last"]=>
    string(6) "Turing"
  }
  [1]=>
  array(2) {
    ["name"]=>
    string(6) "Albert"
    ["last"]=>
    string(8) "Einstein"
  }
  [2]=>
  array(2) {
    ["name"]=>
    string(11) "Hans Albert"
    ["last"]=>
    string(8) "Einstein"
  }
  [3]=>
  array(2) {
    ["name"]=>
    string(16) "Lieserl Einstein"
    ["last"]=>
    string(8) "Einstein"
  }
  [4]=>
  array(2) {
    ["name"]=>
    string(6) "Mileva"
    ["last"]=>
    string(8) "Einstein"
  }
}

After

array(5) {
  [0]=>
  array(2) {
    ["name"]=>
    string(6) "Albert"
    ["last"]=>
    string(8) "Einstein"
  }
  [1]=>
  array(2) {
    ["name"]=>
    string(11) "Hans Albert"
    ["last"]=>
    string(8) "Einstein"
  }
  [2]=>
  array(2) {
    ["name"]=>
    string(16) "Lieserl Einstein"
    ["last"]=>
    string(8) "Einstein"
  }
  [3]=>
  array(2) {
    ["name"]=>
    string(6) "Mileva"
    ["last"]=>
    string(8) "Einstein"
  }
  [4]=>
  array(2) {
    ["name"]=>
    string(4) "Alan"
    ["last"]=>
    string(6) "Turing"
  }
}