Question

I have two arrays of animals (for example).

$array = array(     array(         'id' => 1,         'name' => 'Cat',     ),     array(         'id' => 2,         'name' => 'Mouse',     ) );  $array2 = array(     array(         'id' => 2,         'age' => 321,     ),     array(         'id' => 1,         'age' => 123,     ) ); 

How can I merge the two arrays into one by the ID?

Answer 1

This does what Erik suggested (id no. as array key) and merges vlaues in $array2 to $results.

$results = array();  foreach($array as $subarray) {     $results[$subarray['id']] = array('name' => $subarray['name']); }  foreach($array2 as $subarray) {     if(array_key_exists($subarray['id'], $results))     {         // Loop through $subarray would go here if you have extra          $results[$subarray['id']]['age'] = $subarray['age'];     } }