title: MySQL - Select Query
body: <p>I am some hours trying to make a query, but I haven't sucess! :(</p>
  
  <p>With this query I select <code>users_id</code> and <code>purchase_date</code> of users that bought by key:</p>
  
  <pre><code>SELECT user_id, purchase_date FROM purchases AS p
  INNER JOIN keys AS pc
  ON p.transaction_id = pc.unique_id
  WHERE pc.generator_id = 96768
  GROUP BY user_id
  </code></pre>
  
  <p>Now I want select from these users who bought after this.
  Eg.: <code>SELECT * FROM purchases WHERE user_id = {users of query above} AND purchase_date &gt; {purchase_date of query above}</code></p>