title: WP_Query not ordered correctly
body: <p>I have a custom post type <code>cota</code> where all data is displayed in a <code>&lt;table&gt;</code> in my site. I need to order this table by:</p>
  
  <ul>
  <li><code>administradora</code> - some kind of "category" that the user specifies. Ordered ASC (a-z);</li>
  <li><code>valor</code> - The price of the <code>cota</code>. Each <code>cota</code> has a price. Ordered DESC (9 - 0) ;</li>
  </ul>
  
  <p><strong>The problem</strong> : It's already ordered by <code>administradora</code>, but not correctly ordered by <code>valor</code>. </p>
  
  <p>Example: The order by <code>valor</code> displays first a <code>cota</code> with US$9.000,00 and then another <code>cota</code> with US$1.000.000,00. It's wrong. The one million dollar <code>cota</code> should come first, and then the nine thousand  dollars <code>cota</code>. </p>
  
  <p><a href="https://imgur.com/iD3HMzU" rel="nofollow noreferrer">Here's an image that shows better the situation</a>  </p>
  
  <p><strong>Code for ordering the <code>cota</code>:</strong></p>
  
  <pre><code>      $query = new WP_Query( array(
        'post_type' =&gt; 'cota',
        'posts_per_page' =&gt; -1,
        'tax_query' =&gt; array(
            array(
                'taxonomy' =&gt; 'tipo',
                'field'    =&gt; 'slug',
                'terms'    =&gt; $atts['tipo'],
            ),
        ),
        'orderby' =&gt; 'meta_value_num',
        'meta_query' =&gt; array(
          'relation' =&gt; 'AND',
          'valor_clause' =&gt; array(
            'key' =&gt; 'valor',
            'compare' =&gt; 'EXISTS'
          ),
          'adm_clause' =&gt; array(
            'key' =&gt; 'administradora',
            'compare' =&gt; 'EXISTS'
          )
        ),
        'orderby' =&gt; array(
          'adm_clause' =&gt; 'ASC',
          'valor_clause' =&gt; 'DESC'
        )
      )
    );
  </code></pre>
  
  <p><strong>EDIT 1</strong>: After some research, i found out that wordpress saves all its data as <code>longtext</code> in the database. But still cannot solve the problem.</p>
  
  <p>I can provide more info if needed.</p>