title: Select sold and unsold products
body: <p>I'm trying to select all products names and how many has been sold in current date, but I'm having a problem since not all products are sold everyday. (When the product has not been sold it must return 0)</p>
  
  <p>TABLE PRODUCTS</p>
  
  <pre><code>ID         NAME
  1          APPLE
  2          PINEAPPLE
  3          COFFE
  </code></pre>
  
  <p>TABLE SALES</p>
  
  <pre><code>ID         DATE
  1          2014-01-13
  2          2014-01-13   
  </code></pre>
  
  <p>TABLE PRODUCTS_AND_SALES</p>
  
  <pre><code>SALE_ID    PRODUCT_ID      AMOUNT
  1          3               2
  1          1               1
  2          3               1
  </code></pre>
  
  <p>What I expect to receive:</p>
  
  <pre><code>PRODUCT        AMOUNT
  APPLE          1
  PINEAPPLE      0
  COFFE          3
  </code></pre>
  
  <p>What I receive:</p>
  
  <pre><code>PRODUCT        AMOUNT
  APPLE          1
  COFFE          3
  </code></pre>
  
  <p>My query:</p>
  
  <pre><code>select product, sum(amount) from products
  join products_and_sales using (product_id)
  join sales using (sale_id)
  where date(dt_sale) = curdate()
  group by product_id;
  </code></pre>