title: Reduce INNER JOINs
body: <p>I have the following SQL-Select (SQLite/MySQL):</p>
  
  <pre><code>SELECT products.* FROM products
  INNER JOIN specifications AS spec1 ON specifications.product_id = product.id
  INNER JOIN specifications AS spec2 ON specifications.product_id = product.id
  
  WHERE products.language = "de"
  AND products.category = "ABC"
  
  
  AND (spec1.name = 'Innenabmessungen' AND spec1.value = '182x53')
  AND (spec2.name = 'Farbe'            AND spec2.value = 'schwarz')
  </code></pre>
  
  <p>Is there a solution to use only one <code>INNER JOIN</code>? The problem is that I want to make <code>SELECT</code>s with more than two spec-filter. Is this possible?</p>