- array_diff_assoc: documentation ( source)
- var_dump: documentation ( source)
- array_values: documentation ( source)
<?php
echo 'Hello World';
$sql = [1 => ["id" => 1, "num" => "123"], 2 => ["id" => 2, "num" => "456"]];
$mongo = ["id" => 1, "num" => "123"];
$a = array_diff_assoc ($mongo, array_values($sql));
var_dump($a);