How to Sort a PHP Array by Multiple Fields?

PHP: Sorting an Array by Multiple Field Values

Question:

How can I sort an array in PHP by two or more field values, similar to using the "ORDER BY" clause in SQL?

Example Array:

$data = [
    [
        "destination" => "Sydney",
        "airlines" => "airline_1",
        "one_way_fare" => 100,
        "return_fare" => 300
    ],
    [
        "destination" => "Sydney",
        "airlines" => "airline_2",
        "one_way_fare" => 150,
        "return_fare" => 350
    ],
    [
        "destination" => "Sydney",
        "airlines" => "airline_3",
        "one_way_fare" => 180,
        "return_fare" => 380
    ]
];

Desired Sorting:

Sort the array in ascending order of "return_fare" and then in ascending order of "one_way_fare".

Answer:

The correct PHP function to sort an array by multiple field values is array_multisort(). Here's an example of how to achieve the desired sorting:

// Extract the relevant columns
$return_fare = array_column($data, 'return_fare');
$one_way_fare = array_column($data, 'one_way_fare');

// Sort the array
array_multisort($return_fare, SORT_ASC, $one_way_fare, SORT_ASC, $data);

Simplified Usage with array_orderby()

You can simplify the code using the array_orderby() function from PHP's manual:

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

Array with Arrays (Loops vs. array_column())

If your array contains arrays, you can use a loop to extract the relevant values before sorting:

$return_fare = [];
$one_way_fare = [];

foreach ($data as $row) {
    $return_fare[] = $row['return_fare'];
    $one_way_fare[] = $row['one_way_fare'];
}

Or, if using PHP 5.5 or later, you can use array_column():

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

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