Viewing documents in .PDF in different folders

Good morning! I have a panel where several PDF files are posted, however there are 3 different folders according to each file type. And in that panel, I need to put a method where the person can view the file. But I do not know how to do this search in different folders.

Here is the snippet of code that lists the files:

    </tr>
    <?
      $sql = "SELECT * FROM 'pdf'";
      $query = mysqli_query($conectar, $sql);
      //var_dump($resultado);exit;
      while($listar = mysqli_fetch_assoc($query)){
    ?> 
        <tr>
          <td><?=$listar["nome"]?></td>
          <td><?if($listar["tipo"] == 1)echo"Licitações";
                if($listar["tipo"] == 2)echo"Edital";
                if($listar["tipo"] == 3)echo"Legislação";?></td>
          <td><a href="" class="btn btn-default" target="_blank">
                <span class="glyphicon glyphicon-download"></span> Download</td>
          <td><a href="" class="btn btn-default btn-sm help" data-toggle="modal" title="Excluir PDF"><span class="glyphicon glyphicon-trash"></span></a></td>
        </tr>    
      <?}?> 

As you can see, there is the Uploads folder, and within the legislation, bids and edicts. Where is each file type. When listing, I put it to download the file, but I do not know how to fetch that file in different folders.