title: select users have more than one distinct records in mysql
body: <p>For a table that holds the records of user's webpages visiting behavior, how can I select users that visit more than one webpages.</p>
  
  <p>The structure of this tables is:</p>
  
  <pre><code>userId        webpageId       visitTime
    0              123            ...
    0              124            ...
    1              123            ...
   ...             ...            ...
  </code></pre>
  
  <p>I can count using:</p>
  
  <pre><code>SELECT userId, COUNT(DISTINCT webpageId) AS count FROM visits GROUP BY userId;
  </code></pre>
  
  <p>It gives me the result like:</p>
  
  <pre><code>userId          count
    0               2
    1               1
    2               6
   ...             ...
  </code></pre>
  
  <p>How can I excute query that gives me the final result like:</p>
  
  <pre><code>userId
    0
    2
   ...
  </code></pre>
  
  <p>each is user that visit more than one DISTINCT webpages </p>