#array_search - recherche dans un tableau multidimensionnel #http://php.net/manual/fr/function.array-search.php in (PHP 5 >= 5.5.0) you don't have to write your own function to search through a multi dimensional array ex : $userdb=Array ( (0) => Array ( (uid) => '100', (name) => 'Sandra Shush', (url) => 'urlof100' ), (1) => Array ( (uid) => '5465', (name) => 'Stefanie Mcmohn', (pic_square) => 'urlof100' ), (2) => Array ( (uid) => '40489', (name) => 'Michael', (pic_square) => 'urlof40489' ) ); simply u can use this $key = array_search(40489, array_column($userdb, 'uid'));