title: count(*) vs count(column-name) - which is more correct?
body: <p>Does it make a difference if you do <code>count(*)</code> vs <code>count(column-name)</code> as in these two examples?</p>
  
  <p>I have a tendency to always write <code>count(*)</code> because it seems to fit better in my mind with the notion of it being an aggregate function, if that makes sense. </p>
  
  <p>But I'm not sure if it's technically best as I tend to see example code written without the <code>*</code> more often than not.</p>
  
  <p><strong>count(*):</strong></p>
  
  <pre><code>select customerid, count(*), sum(price) 
  from items_ordered
  group by customerid
  having count(*) &gt; 1;
  </code></pre>
  
  <p><strong>vs. count(column-name):</strong></p>
  
  <pre><code>SELECT customerid, count(customerid), sum(price)
  FROM items_ordered
  GROUP BY customerid
  HAVING count(customerid) &gt; 1;
  </code></pre>