How can I merge PHP arrays? 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: This does what Erik suggested (id no. as array key) and merges vlaues in $array2 to $results. $results =