Question

I have a table with the following:

+----+-------+-------+-----------+-----------+--------------+--------------+
| id | stock | price | usedStock | usedPrice | specialStock | specialPrice |
+----+-------+-------+-----------+-----------+--------------+--------------+
| #1 |     1 | 10.00 |         0 | 0         |            0 | 0            |
| #2 |     0 | 0     |         1 | 15.00     |            1 | 20.00        |
| #3 |     0 | 0     |         0 | 11.00     |            1 | 14.00        |
+----+-------+-------+-----------+-----------+--------------+--------------+

I would like to create a query that orders by lowest price first if the type of item is in stock.

So the query would result in the following order:

#1 - 10.00 (because 10.00 is the lowest result)
#3 - 14.00 (because although 11.00 is less, it's not in stock)
#2 - 15.00 (because 15.00 is lower than 20.00)

I’ve added the PHP tag to this question in case there’s a quicker way of calculating using PHP after selecting the table.

Answer 1

I would order by the least price, in case item is present in stock:

ORDER BY
  LEAST(CASE WHEN stock        THEN price        ELSE GREATEST(price, usedPrice, specialPrice) END,
        CASE WHEN usedStock    THEN usedPrice    ELSE GREATEST(price, usedPrice, specialPrice) END,
        CASE WHEN specialStock THEN specialPrice ELSE GREATEST(price, usedPrice, specialPrice) END)

If the condition is true (>=1), each CASE WHEN will return the price, otherwise it will return the greatest price. Fiddle here.