Online PHP editor | output for bnRrP

<?php $data = [ [ [ 'Date' => '2021-03-15T00:00:00.0000000+01:00', 'Arena' => ['Id' => 181796, 'Name' => 'Motala bibliotek'], 'Description' => null, 'IsCanceled' => null ], [ 'Date' => '2021-03-16T00:00:00.0000000+01:00', 'Arena' => ['Id' => 181796, 'Name' => 'Motala bibliotek'], 'Description' => null, 'IsCanceled' => null ], [ 'Date' => '2021-03-17T00:00:00.0000000+01:00', 'Arena' => ['Id' => 181796, 'Name' => 'Motala bibliotek'], 'Description' => null, 'IsCanceled' => null ] ], [ [ 'Date' => '2021-03-15T00:00:00.0000000+01:00', 'Arena' => ['Id' => 181796, 'Name' => 'Motala bibliotek'], 'Description' => null, 'IsCanceled' => null ], [ 'Date' => '2021-03-16T00:00:00.0000000+01:00', 'Arena' => ['Id' => 181796, 'Name' => 'Motala bibliotek'], 'Description' => null, 'IsCanceled' => null ] ] ]; var_export( array_column(array_merge(...$data), 'Date') ); echo "\n---\n"; $result1 = []; array_walk_recursive( $data, function($v, $k) use (&$result1) { if ($k === 'Date') { $result1[] = $v; } } ); var_export($result1); echo "\n---\n"; $result2 = []; foreach ($data as $group) { array_push($result2, ...array_column($group, 'Date')); } var_export($result2); echo "\n---\n"; $result3 = []; foreach ($data as $group) { foreach ($group as $row) { if (array_key_exists('Date', $row)) { $result3[] = $row['Date']; } } } var_export($result3); echo "\n---\n"; $result4 = []; foreach ($data as $group) { foreach ($group as ['Date' => $result4[]]); } var_export($result4);