title: Left join, sum and count group by
body: <p>I have 3 tables: goods, store and pics. In the first table goods titles are stored. In the second - balance of goods in different stocks, in the third - links to goods pictures. So goods has one-to-many connection with store and pics.
  Now, I need to get a list of goods with sum of stock rests and count of pictures by one query.
  I did it like this:</p>
  
  <pre><code>SELECT good.id, good.title, sum(store.rest) AS storerest, count(pics.id) AS picscount 
  FROM goods 
  LEFT JOIN store ON (goods.id = store.goodid) 
  LEFT JOIN pics ON (goods.id = pics.goodid) 
  GROUP BY goods.id`
  </code></pre>
  
  <p>All seems ok while good has 0 or 1 picture. But when it has 2 - storerest doubles, and I can't understand why.
  What's wrong?</p>