title: PHP escape certain $_post value out of loop
body: <p>I got a form which passes dynamic stock qty send to update in database, as below:</p>
  
  <pre><code>if($_POST) {
  
      $cid = $_POST['prod_id'];
  
      foreach($_POST as $key =&gt; $value){
          $q  = "UPDATE `stock` SET";
          $q .= " in_stock=in_stock + '".$value."'";
          $q .= " WHERE cid='".$cid."' AND sid='".$key."'";
  
          echo $q.'&lt;br /&gt;';
      }
  
  }
  </code></pre>
  
  <p>However, the echo queries is output like:</p>
  
  <pre><code>UPDATE `stock` SET in_stock=in_stock + '2' WHERE cid='2' AND sid='prod_id'
  UPDATE `stock` SET in_stock=in_stock + '1' WHERE cid='2' AND sid='qty-2'
  UPDATE `stock` SET in_stock=in_stock + '2' WHERE cid='2' AND sid='qty-3'
  UPDATE `stock` SET in_stock=in_stock + '3' WHERE cid='2' AND sid='qty-4'
  UPDATE `stock` SET in_stock=in_stock + '8' WHERE cid='2' AND sid='qty-5'
  </code></pre>
  
  <p>The first query should not be include in a loop, but that is part of $_post input for <code>cid</code>, is there any workaround to escape the first query out of the update loop?</p>