title: SQL sub-select returns 2 columns - expected 1
body: <pre><code>sqlite&gt; SELECT *
     ...&gt; FROM Studio
     ...&gt; WHERE third_party_id NOT IN (
     ...&gt; SELECT third_party_id,effeciency_rating
     ...&gt; FROM Staff
     ...&gt; WHERE Staff.third_party_id = Studio.third_party_id AND
     ...&gt; Staff.effeciency_rating &lt; 0.7
     ...&gt; );
  </code></pre>
  
  <p>with the error message</p>
  
  <blockquote>
    <p>sub-select returns 2 columns - expected 1</p>
  </blockquote>
  
  <p>So I know why this happens, my subselct has thirdpartyid and effeciency rating while I only select thirdpartyid from Studio.</p>
  
  <p>So my relation: Stuido employs staff
  So now I want to select all studios that didnt employ a staff with effeciency rating under 0.7.</p>
  
  <p>So my question is how do I select my staff based on effeciency rating and give my studio back?</p>