Question

I would like to get something like this:

*Customer    *2009     *2010    *
|------------|---------|--------|
|Peter       |120      |240     |
|Johe        |455      |550     |

My first approach to the query was this:

Select c.name, sum(o2009.price), sum(o2010.price) from customer c
join orders o2009 on (o2009.customerId = c.id AND o2009.year = 2009)
join orders o2010 on (o2010.customerId = c.id AND o2010.year = 2010)
group by c.id

Unfortunately this is completely wrong. I guess I could run 2 queries and then build a union, but maybe there is something simpler?

Answer 1

Just modifying one of the answers to get customers with no orders –

Select c.name, 
   Sum(Case When o.year == 2008 Then price Else 0 End) cy2008,
   Sum(Case When o.year == 2009 Then price Else 0 End) cy2009,
   Sum(Case When o.year == 2010 Then price Else 0 End) cy2010
From Customers c left outer join 
     Orders o on o.customer_id = c.customer_id
Group By c.name