title: I cant update the reserve of products in Database
body: <p>I am building an e-shop, and I want to update the reserve on products in the database but the code is not working properly. Can you check it out, please</p>
  
  <pre><code>if (filter_input(INPUT_GET,'checkout')){
  $sql="UPDATE tblproduct SET apothema=18 WHERE id=1"}
  </code></pre>