title: Possible to calculate SUM over all entries while limiting output in same query?
body: <p>I have a complex query that consists of JOINs, GROUP BYs and complex WHEREs. Because there are many rows, the output is limited to 100 rows per page (paginated). I can NOT remove the limit and limit in app code.</p>
  
  <p>However, I need the count and sum of a column for all entries that match the query. For the count I can use <code>SQL_CALC_FOUND_ROWS</code>, for the sum I see no way around a second query for now - am I wrong?</p>
  
  <p>Since SqlFiddle won't work, here is a simplified example:
  (I <strong>need a total sum of all p.amount</strong>'s or a SUM of the p_sum's.)</p>
  
  <pre><code>CREATE TABLE users
      (`customer_id` int, `company` varchar(255), `belongstoclient` int)
  ;
  CREATE TABLE something
      (`id` int, `customer_id` int, `amount` int, `type` int)
  ;
  
  INSERT INTO users
      (`customer_id`, `company`, `belongstoclient`)
  VALUES
      (1, 'Company A', 1),
      (2, 'Company B', 1),
      (3, 'Company C', 2),
      (4, 'Company D', 1)
  ;
  
  INSERT INTO something
      (`id`, `customer_id`, `amount`, `type`)
  VALUES
      (1, 1, 17, 2),
      (2, 2, 34, 3),
      (3, 2, 20, 2),
      (4, 4, 13, 2),
      (5, 3, 11, 2)
  ;
  </code></pre>
  
  <p>With the (simplified) query:</p>
  
  <pre><code>SELECT SQL_CALC_FOUND_ROWS 
      u.customer_id as `customer_id`,
      u.company as `company`,
      COUNT(p.id) as `p_count`,
      SUM(p.amount) as `p_sum`,
      p.type as `p_type`
  FROM `users` u
  LEFT JOIN `something` p 
  ON p.customer_id=u.customer_id
  WHERE u.belongstoclient=1 
  GROUP BY p.type
  ORDER BY u.customer_id
  DESC LIMIT 0,100
  </code></pre>