Question

this statement will generate a 4 column table:

SELECT shipped.badguy AS badguy, shipped.sdate AS LineDate,
        'Delivery' AS Legend, -price*quantity AS amount
    FROM product JOIN shipped ON (product.id = shipped.product)
UNION
  SELECT receipt.badguy, receipt.rdate,notes, amount
  FROM receipt

how do i get the total sum of the 4th of column of what the above generates?

Answer 1

I like to use subqueries for everything.

SELECT SUM(results.amount)
FROM
(
SELECT -price*quantity AS amount 
    FROM product JOIN shipped ON (product.id = shipped.product) 
UNION 
  SELECT amount 
  FROM  
...
) results