title: sql query in a performant way
body: <p>In my case there is a table called ServiceCarrier as below:  </p>
  
  <pre><code>ServiceId CarrierId
  
  1         1  
  2         1  
  4         1  
  1         2  
  2         2  
  5         2   
  1         20028  
  2         20028  
  5         20028  
  </code></pre>
  
  <p>I want to group it by CarrierId and want to get the intersection in between grouped ones.
  my expected result is as below </p>
  
  <pre><code>ServiceId 
  1  
  2  
  </code></pre>