Try this..... You can use this function for any depth of the associated array. Just contraint to this function is that the key value would not be repeat any where in array.
<?php
function is_in_array($array, $key, $key_value){
$within_array = 'no';
foreach( $array as $k=>$v ){
if( is_array($v) ){
$within_array = is_in_array($v, $key, $key_value);
if( $within_array == 'yes' ){
break;
}
} else {
if( $v == $key_value && $k == $key ){
$within_array = 'yes';
break;
}
}
}
return $within_array;
}
$test = array(
0=> array('ID'=>1, 'name'=>"Smith"),
1=> array('ID'=>2, 'name'=>"John")
);
print_r(is_in_array($test, 'name', 'Smith'));
?>