title: Removing entries with missing links
body: <p>I have two tables</p>
  
  <p>Number 1:</p>
  
  <pre><code>adresse
    id    name
  </code></pre>
  
  <p>Number 2:</p>
  
  <pre><code>produkte
    id    anbieter    
  </code></pre>
  
  <p>Details:</p>
  
  <pre><code>id: int
  name: string
  anbieter: int
  </code></pre>
  
  <p>Each anbieter in produkte is to be an id in adresse. For example:</p>
  
  <pre><code>adresse
    id  name
    1   hello
    2   there
  
  produkte
    id  anbieter    
    1   1
    2   1
    3   2
    4   1
  </code></pre>
  
  <p>Works, but</p>
  
  <pre><code>adresse
    id  name
    1   hello
    2   there
  
  produkte
    id  anbieter    
    1   4
    2   1
    3   2
    4   1
  </code></pre>
  
  <p>doesn't because there is no adresse.id of produkte.anbieter = 4</p>
  
  <p>My goal is to remove every entry of produkte whose anbieter does not have an adresse.id.   </p>