Handling negative values with sql

Question

I have a data set that lists the date and quantity of future stock of products. Occasionally our demand outstrips our future supply and we wind up with a negative future quantit

Answer 1

You don't seem to get a lot of answers - so here's something if you won't get the right 'how-to do it in pure SQL'. Ignore this solution if there's anything SQLish - it's just a defensive coding, not elegant.

If you want to get a sum of all data with same season why deleting duplicate records - just get it outside, run a foreach loop, sum all data with same season value, update table with the right values and delete unnecessary entries. Here's one of the ways to do it (pseudocode):

productsArray = SELECT * FROM products
processed = array (associative)
foreach product in productsArray:
  if product[season] not in processed:
    processed[season] = product[quantity]
    UPDATE products SET quantity = processed[season] WHERE id = product[id]
  else:
    processed[season] = processed[season] + product[quantity]
    DELETE FROM products WHERE id = product[id]