<input type="checkbox" id="goods_server_name" name="goods_server_name[]" value="1 "  >1

<input type="checkbox" id="goods_server_name" name="goods_server_name[]" value="2 "  >2

<input type="checkbox" id="goods_server_name" name="goods_server_name[]" value="3 "  >3

<input type="checkbox" id="goods_server_name" name="goods_server_name[]" value="4 "  >4

$str_tag="";

$s=$_POST['goods_server_name'];

for($i=0;$i<count($s);$i++){

 if($i==0){

   $str_tag = $s[$i];

 }else{

  $str_tag = $str_tag .",".$s[$i];

 }
}