SQL Selecting multiple sums?

Question

Let\'s say I have a table:

SELECT  SUM(quantity) AS items_sold_since_date,
        product_ID
FROM    Sales
WHERE order_date >= \'01/01/09\'
GROUP BY product_         


        

Answer 1

SELECT  SUM(CASE WHEN order_date >= '01/01/09' THEN quantity ELSE 0 END) AS items_sold_since_date,
        SUM(quantity) AS items_sold_total,
        product_ID
FROM    Sales
GROUP BY product_ID