Create persistence of categories and subcategories with jquery

Now I have a persistence problem in the select field of categories and subcategories that I did with jquery with the help of a video, since I'm not very good with jquery.

I have the following jquery script:

<script type="text/javascript">
   $(document).ready(function () {

     $("select[name=post_category]").change(function () {
        $("select[name=post_category_parent]").html('<option value="0">Carregando...</option>');

         $.post("<?= INCLUDE_PATH ?>/modulos/combo_subcategoria.php",
                {post_category: $(this).val()},
                function (valor) {
                     $("select[name=post_category_parent]").html(valor);
                }
         )
       })
   })
</script>

And I have my selects:

<div class="form-group">
      <label for="post_category"><strong>Categoria</strong></label>
      <select name="post_category" id="post_category" class="subcategoria form-control" required="">
           <option value="" disabled="" selected="">Selecione a categoria</option>
           <?php
              $cattype = 'categoria';
              $type = "evento";
              $read->ExeRead("ws_categories", 
                             "where category_type = :cattype and type = :type and category_parent = 0", 
                             "cattype={$cattype}&type={$type}");
              if ($read->getResult()):
                  foreach ($read->getResult() as $cat_form):
           ?>                                                                                
          <option value="<?= $cat_form->category_id; ?>"><?= $cat_form->category_title; ?></option>
          <?php
                  endforeach;
              endif;
          ?>
        </select>
</div>
<div class="form-group">
       <label for="post_category_parent"><strong>Subcategoria</strong></label>
       <select name="post_category_parent" id="post_category_parent" class="subcategoria form-control" required="">
             <option value="" disabled="" selected="">Subcategoria</option>
             <option value="" disabled="">Selecione a categoria</option>
      </select>
</div>

I wanted to be persistent with the data that is in the database, so that the user when editing the post, has to be selecting categories and subcategories again.