title: SQL: ... WHERE X IN (SELECT Y FROM ...)
body: <p>Is the following the most efficient in SQL to achieve its result:</p>
  
  <pre><code>SELECT * 
    FROM Customers 
   WHERE Customer_ID NOT IN (SELECT Cust_ID FROM SUBSCRIBERS)
  </code></pre>
  
  <p>Could some use of joins be better and achieve the same result?</p>