PHP sort array by two field values

I've an array like this

Array (
[0] => Array( "destination" => "Sydney",
"airlines" => "airline_1",
"one_way_fare" => 100,
"return_fare => 300
),
[2] => Array( "destination" => "Sydney",
"airlines" => "airline_2",
"one_way_fare" => 150,
"return_fare => 350
),
[3] => Array( "destination" => "Sydney",
"airlines" => "airline_3",
"one_way_fare" => 180,
"return_fare => 380
)
)

How can i sort the value by return_fare asc , one_way_fare asc ?

I tried array_multisort() but i ended up getting mixed up data..

asort only works for one dimensional array, i need to sort by two values or more, how can i achieve this like in SQL, order by field1 asc,field2 asc ?

array_multisort() is the correct function, you must have messed up somehow:

// Obtain a list of columns
foreach ($data as $key => $row) {
    $return_fare[$key]  = $row['return_fare'];
    $one_way_fare[$key] = $row['one_way_fare'];
}

// Sort the data with volume descending, edition ascending
array_multisort($data, $return_fare, SORT_ASC, $one_way_fare, SORT_ASC);

If you take a look at the comments at PHP's manual page for array_multisort(), you can find a very helpful array_orderby() function which allows you to shorten the above to just this:

$sorted = array_orderby($data, 'return_fare', SORT_ASC, 'one_way_fare', SORT_ASC);

To avoid the looping use array_column() (as of PHP 5.5.0):

array_multisort(array_column($data, 'return_fare'),  SORT_ASC,
                array_column($data, 'one_way_fare'), SORT_ASC,
                $data);

In addition to array_multisort(), which requires you to build column-arrays first, there is also usort() which doesn't require such a thing.

usort($data, function($a, $b) { 
    $rdiff = $a['return_fare'] - $b['return_fare'];
    if ($rdiff) return $rdiff; 
    return $a['one_way_fare'] - $b['one_way_fare']; 
}); // anonymous function requires PHP 5.3 - use "normal" function earlier

Another example using the spaceship operator.

usort($data, function($a, $b) { 
    return $a['return_fare'] <=> $b['return_fare'] ?: $a['one_way_fare'] <=> $b['one_way_fare'];
});

Or you can use uasort as follows

uasort($arr, function($a,$b){
    $c = $a['return_fare'] - $b['return_fare'];
    $c .= $a['one_way_fare'] - $b['one_way_fare'];
    return $c;
});

Fiddle

I'll answer this in a way that can be generalized, no matter how many items you wish to sort on!

Sorting on return_fare then one_way_fare:

usort($data, function($a, $b) {
   if ($a['return_fare'] != $b['return_fare']) {
      return $a['return_fare'] <=> $b['return_fare'];
   }
   
   return $a['one_way_fare'] <=> $b['one_way_fare'];
});

Sorting on return_fare, then one_way_fare, then destination:

usort($data, function($a, $b) {
   if ($a['return_fare'] != $b['return_fare']) {
      return $a['return_fare'] <=> $b['return_fare'];
   }

   if ($a['one_way_fare'] != $b['one_way_fare']) {
      return $a['one_way_fare'] <=> $b['one_way_fare'];
   }
   
   return strnatcasecmp($a['destination'], $b['destination']);
});

Sorting on just return_fare:

usort($data, function($a, $b) {
   return $a['return_fare'] <=> $b['return_fare'];
});

Note: you don't have to use an anonymous function with usort!

function cmp($a, $b) {
   return $a['return_fare'] <=> $b['return_fare'];
}

usort($data, 'cmp');


// Use a function inside a class:
class MyClass {
   public static function compare($a, $b) {
      return $a['return_fare'] <=> $b['return_fare'];
   }
}

usort($data, ['MyClass', 'compare']);

You can also chain these using the Elvis Operator (?:):

usort($data, function($a, $b) {
      return $a['return_fare'] <=> $b['return_fare'] ?:
             $a['one_way_fare'] <=> $b['one_way_fare'] ?:
             strnatcasecmp($a['destination'], $b['destination']);
});

This last example used the Spaceship Operator (<=>) and the Elvis Operator (?:). Isn't programming great?

Ohh, i managed to solve my own question again....

function array_multi_sort($array, $on1,$on2, $order=SORT_ASC) 
{

    foreach($array as $key=>$value){
        $one_way_fares[$key] = $value[$on2];
        $return_fares[$key] = $value[$on1];
    }

    array_multisort($return_fares,$order,$one_way_fares,$order,$array);
}

The thing is i missed out the last parameter $array on array_multisort($return_fares,$order,$one_way_fares,$order,$array);

earlier!