getting multiple values from checkboxes and storing in DB php

Question

Having trouble storing multiple checkbox values into DB. Not sure if this is the most efficient way but it's the only thing I could come up with. If there are better ways to do it please share. I am still in test mode so there is no validation yet.

ITEMS COMING FROM DB

 $get_products = $db->prepare("select * from item where user_id = '$id' ORDER BY add_date");

 $get_products->execute();

 while ($row = $get_products->fetch())
 {
   $item_id =  $row['item_id'];
   $user_id =  $row['user_id'];
   $item_name = $row['item_name'];

   $products .= "<br/><input type='checkbox' name='items[]' value='$item_id' />$item_name";
 }

FORM

<form method="post" action="confirm.php">

    <?php echo $products; ?>

    <input type="submit" value="Add Items" id="add_items"/>

    <input name="from_id" type="hidden" value="1">
    <input name="to_id" type="hidden" value="2">
    <input type="submit" name="submit" value="Submit" >
 </form>

PROCESS

if(isset($_POST['submit']))
{
         $from = $_POST['from_id'];
     $to = $_POST['to_id'];
     $items = $_POST['items'];

   if(empty($items))
   {
      $message = "no items in items";
      exit;
   }

        foreach($items as $i)
    {
          $items .= $i. "|";
    }
         json_encode($items);

$sql = $db->prepare("INSERT into trans(from_id, to_id,items)VALUES(:from_id, 
                         :to_id, :items");

$sql->bindValue('from_id', $from);
$sql->bindValue('to_id', $to);
$sql->bindValue('items', $items);

if($sql->execute())
{
    header("Location: profile.php?user=1");
    exit();
    }

Answer 1

The first issue I see is that you are overwriting your $items variable with a blank string when you do this:

$items = $_POST['items'];

$items = "";

This means you will be running a foreach on a blank string.

Although a better way to store the values from your checkboxes would be to just json_encode() the original $items variable. This will encode the value you receive from your form into a JSON string which can safely be stored in a database.

Then when you want to get the data back out of the database, simply run json_decode() on the JSON string and the JSON string will be converted back to an array.

Though, if you want an associative array to be returned from json_decode() , be sure to pass true into the second parameter like so:

$indexed_array = json_decode($some_array);
$associative_array = json_decode($some_array, true);

EDIT

Providing the data is being passed from the form, this is what you will need in your confirm.php file:

if(isset($_POST['submit']))
{
  $from = $_POST['from_id'];
  $to = $_POST['to_id'];
  $items = $_POST['items'];

  if(empty($items))
  {
    $message = "no items in items";
    exit;
  }

  $items = json_encode($items);

  $sql = $db->prepare("INSERT into trans(from_id, to_id,items)VALUES(:from_id, 
                     :to_id, :items");

  $sql->bindValue('from_id', $from);
  $sql->bindValue('to_id', $to);
  $sql->bindValue('items', $items);

  if($sql->execute())
  {
    header("Location: profile.php?user=1");
    exit();
  }
}