Question

I know this has been asked a dozen times here at stackoverflow, but it is driving me mad.

I have two tables:

1. card_lookup_values (which contains: card_id, card_price)
2. card_sales (which contains: discount_price)

They both contain card_id (so I know I can join them there), but how exactly would I join them? What I am trying to accomplish is to multiply the card’s price it’s discount price to get the actual sale price, but it is proving to be a real head scratcher.

Answer 1

SELECT 
  card_lookup_values.card_id,
  card_lookup_values.card_price,
 card_sales.discount_price,
  card_sales.discount_price * card_lookup_values.card_price AS actual_price
FROM card_lookip_values JOIN card_sales ON card_lookup_values.card_id = card_sales.card_id

Or, if your discounts are something like “20% off”, the following subtracts the amount discounted (discount * original) from the original to return the new price.

card_lookup_values.card_price - (card_sales.discount_price * card_lookup_values.card_price) AS actual_price