Online PHP editor | refs for BrBMJ

<?php $a[] = ["name" => "aaaaa", "projectId" => 0, "area" => "AreaX"]; $a[] = ["name" => "bbbbb", "projectId" => 2, "area" => ""]; $b[] = ["name" => "cccc", "projectId" => 1, "area" => ""]; $b[] = ["name" => "aaaaa", "projectId" => 0, "area" => "AreaX"]; $col = "projectId"; $res = array_diff(array_column($a, $col), array_column($b, $col)); print_r(array_map(function($id) use ($col) {return [$col => $id];}, $res));