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

you can write

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