title: Many to many and how to get a queryset from queryset
body: <p>I have following models:</p>
  
  <pre><code>class Product(models.Model):
      name = CharField(max_length=30)
  
  class Store(models.Model):
      name = CharField(max_length=30)
      product = models.ManyToManyField(Product)
  </code></pre>
  
  <p>How to get <code>Store</code>s with product named <code>product_name</code> and also, get all the products (except the product with name <code>product_name</code>) ? Is it possible to make it in one query?
  In raw SQL it would be simple <code>JOIN</code>s. Not sure how to implement it via Django.</p>