如何将json_decoded值（仅）保存为$ var中的一个字符串

Im receiving the following variable sent as a json array from javascript: $_REQUEST['fb_friend_uid']

I then decode the array and then do a var_dump

$string = json_encode($_REQUEST['fb_friend_uid']);
$result = json_decode($string, true);

var_dump($result);

The var_dump shows me the following

array (size=360)
  0 => 
    array (size=1)
      'id' => string '263901486' (length=9)
  1 => 
    array (size=1)
      'id' => string '502533736' (length=9)
  2 => 
    array (size=1)
      'id' => string '506526230' (length=9)
  3 => 
    array (size=1)
      'id' => string '507245473' (length=9)
    etc..

How would I go about saving all values from 'id' into one new $var_string ? - formatted like: "263901486, 502533736, 506526230"

Objective is to use the string in an sql query like so:

SELECT * FROM vote WHERE
vote_fb_uid IN ($var_string)

Try this :

$string = json_encode($_REQUEST['fb_friend_uid']);
$result = json_decode($string, true);

$res_array   = array();
foreach($result as $val){
   $res_array[]  = $val['id'];
}

$res_string = implode(",",$res_array);

If you want all the items to be combined to one long string you can try imploding the array http://php.net/manual/en/function.implode.php

$varString = implode(',', $_REQUEST['fb_friend_uid'])

I don't really know PHP, but looking at the docs, you should be able to write something along the lines of:

$string = json_encode($_REQUEST['fb_friend_uid']);
$result = json_decode($string, true);

$res_array = array_map(function ($val) { return $val['id']; });

$res_string = join(",", $res_array);

(Adapted from Prasanth Bendra's answer.)

Try this

$string = json_encode($ar);
$result = json_decode($string, true);

$res_array   = array();
foreach($result as $val){
   $res_array[]  = $val['id'];
}

$res_string = "'".implode("','", $res_array)."'";

$qry = "SELECT * FROM vote WHERE vote_fb_uid IN ($res_string)";