Left Outer Join Example

So I have a products table :

And I have a Sales table:

If I want to find the sales for ALL products including the ones which are not present in the sales table, I can do this ( SQLITE syntax) : select p.productname, case when sum(amount) is null then 0 else sum(s.amount) end as totalsales from product p left outer join sale s on p.productcode = s.productcode where s.productcode is null or s.productcode is not null group by p.productname

One of the best examples I have seen for Outer and Inner joins is at CodingHorror