title: MySQL: Count the distinct rows per day
body: <p>I have an interesting query I need to do. I have a table with an <code>INT</code> column containing ip address numbers (using <code>INET_ATON</code>), and a <code>timestamp</code> column. I want to be able to count the number of unique ip address columns there are per day. That is, how many distinct ip rows there are in each day. So, for example, if an ip address is in the same day twice, it counts as 1 in the final count, however if the same ip address is in another day it'll be counted there will be a second count for it.</p>
  
  <h3>Example Data:</h3>
  
  <pre><code>PK | FK  | ipNum      | timestamp
  11 | 404 | 219395     | 2013-01-06 22:23:56
  7  | 404 | 467719     | 2013-01-06 22:23:41
  8  | 404 | 4718869    | 2013-01-06 22:23:42
  10 | 404 | 16777224   | 2013-01-06 22:23:56
  5  | 404 | 1292435475 | 2013-01-06 22:23:25
  12 | 404 | 1526990605 | 2013-01-06 22:23:57
  6  | 404 | 1594313225 | 2013-01-06 22:23:40
  4  | 404 | 1610613001 | 2013-01-06 22:23:23
  9  | 404 | 1628635192 | 2013-01-06 22:23:55
  1  | 404 | 2130706433 | 2013-01-06 21:29:38
  2  | 407 | 2130706433 | 2013-01-06 21:31:59
  3  | 407 | 2130706433 | 2013-01-06 21:32:22
  </code></pre>