title: Do these 2 sql queries return the same result?
body: <pre><code>select c1, c2 from t1
  where not exists
  (
  select 1 from t2
  where t1.c2 = t2.c3
  )
  </code></pre>
  
  <p>and</p>
  
  <pre><code>select c1, c2 from t1
  where c2 not in 
  (
  select c3 from t2
  )
  </code></pre>