如何将此json数组保存到MYSQL数据库

I want to save this json array that my fb-login returns to a database. However I don't really know how to convert that into a string using php.

[{"id":"108124505876479","name":"Wakeboarding"},{"id":"112003352149145","name":"Bouldering"},{"id":"110008522357035","name":"Handball"}]

I have tried this code below but I am even not quite sure anymore whether what the fb login return is a json array or not.

$json = '{"id":"108124505876479","name":"Wakeboarding"},{"id":"112003352149145","name":"Bouldering"},{"id":"110008522357035","name":"Handball"}';

var_dump(json_decode($json));

How would I be able to save the different sports to my database in a string?

Any help would be much appreciated.

Thanks.

EDIT: The upper part returns NULL.

SECOND EDIT:

if (array_key_exists('sports', $me)){


                    $json = '$me['sports']'; PROBLEM IS HERE
                    $data = json_decode($json, true);
                    $sports = array();
                    foreach ($data as $item) {
                        $sports[] = $item['name'];
                    }

                    $user->fb_sports = $sports;
                }

$json = '[{"id":"108124505876479","name":"Wakeboarding"},{"id":"112003352149145","name":"Bouldering"},{"id":"110008522357035","name":"Handball"}]';
$data = json_decode($json, true);
$sports = array();
foreach ($data as $item) {
    $sports[] = $item['name'];
}

if you want commas separating them:

$output = implode(', ', $sports);

If var_dump(json_decode($json)) returns what you'd expect just save $json directly into the database.

use :

 $json = serialize($json);

$json1 = '{"id":"108124505876479","name":"Wakeboarding"},{"id":"112003352149145","name":"Bouldering"},{"id":"110008522357035","name":"Handball"}';
$json2 = '[{"id":"108124505876479","name":"Wakeboarding"},{"id":"112003352149145","name":"Bouldering"},{"id":"110008522357035","name":"Handball"}]';

var_dump(json_decode($json1,true));
var_dump(json_decode($json2,true));

watch the difference

$string=mysql_real_escape_string($json);