title: How to count some rows of a MySQL table
body: <p>I got a MySQL table were multiple users can click a button to accept something.
  After that, the information get saved with the following data.</p>
  
  <pre><code>uid (ai, primary key)
  user_uid (id of user)
  object_uid (id of object you visit)
  date_start 
  date_end
  </code></pre>
  
  <p>I want to count how many people got <code>date_end</code> on the same <code>object_uid</code>.
  So if 2 people have an entry in <code>date_end</code> it should count for example 2 people which have visited the same <code>object_uid</code>. But I have no clue how to do that and I don't know to google better, because I search for an answer for about 2 hours ago.</p>
  
  <p>Greetings</p>
  
  <p>PS: I'm sorry for my bad English.</p>