php - MySQL - 减少select语句中嵌套公式的长度

Question

如何通过使用先前公式的引用来减少嵌套公式的长度？

例如，我想执行以下操作，但收到错误:

(orders.size_0 + orders.size_1 + orders.size_2 + orders.size_3 + orders.size_4 +     orders.size_5 + orders.size_6) AS tot_qty,
ROUND(tot_qty*orders.order_price,0) AS tot_price,
ROUND(tot_price/f.rate,0) AS price_gbp

谢谢，德里克。

Answer 1

您可以使用子查询，例如 -

SELECT tot_qty, tot_price, ROUND(tot_price / sub1.rate,0) AS price_gbp FROM (
  SELECT tot_qty, ROUND(tot_qty * sub2.order_price, 0) AS tot_price FROM (
    SELECT (orders.size_0 + orders.size_1 + orders.size_2 + orders.size_3 + orders.size_4 + orders.size_5 + orders.size_6) AS tot_qty FROM table
      ...
    ) sub2
  ) sub1