在php中获取多选值

I want to get multiselsect values in PHP. This is my code:

<select id="tableset" class="form-control select2 table_id" name="table_id[]">
  <option value="">Table</option>
  <?php foreach ($tables as $tbls) { ?>
    <option value="<?php echo $tbls->id; ?>"><?php echo $tbls->name; ?></option>
  <?php } ?>
</select>

now to receive the values this is what i am doing

foreach ($_GET['table_id'] as $selectedOption)
{
  echo $selectedOption;
}

I get an error with invalid argument for foreach. Please help me. How can I sort the issue?

First for a multiple select you need to indicate it by adding multiple tag to the select

 <select id="tableset" multiple="multiple" class="form-control select2 table_id" name="table_id[]">
    <option value="">Table</option>
    <?php
    foreach ($tables as $tbls) {
     ?>
    <option value="<?php echo $tbls->id; ?>"><?php echo $tbls->name; ?> 

   </option>
  <?php } ?>

now you can get them

foreach ($_GET['table_id'] as $selectedOption){
   echo $selectedOption;
 }