title: Aggregate Function of a column if there are nulls?
body: <p>If I am running an aggregate function on a column with numerical values such as below:</p>
  
  <pre><code>Select Name, count(Miles) as number from tbl
  </code></pre>
  
  <p>If some names have <code>null</code> values in <code>Miles</code> column, how will that be handled? </p>
  
  <p>If it is a name that has other values it will just not be counted, but if it is name that has only null values and no numbers how will that show up in the output? </p>