How do you get access to the pseudonym column?

[magpie]

SELECT `A`.*,
       SUM(o.quantity) AS `orders`,
       SUM((CASE
                WHEN o.date >= ADDDATE(CURRENT_DATE(), -30 +1) THEN o.quantity
                ELSE 0
            END)) AS `orders_period`,
       SUM(s.quantity) AS `sales`,
       SUM((CASE
                WHEN s.date >= ADDDATE(CURRENT_DATE(), -30 +1) THEN s.quantity
                ELSE 0
            END)) AS `sales_period`,
       ROUND(`sales` / `orders` * 100) AS `buyout`
       
FROM `data_goods` AS A
LEFT JOIN `data_orders` AS o ON o.wb_code = A.wb_code AND o.user = A.user AND o.key = A.key
LEFT JOIN `data_sales` AS s ON s.wb_code = A.wb_code AND s.user = A.user AND s.key = A.key AND s.sale_id LIKE 'S%'
WHERE A.`user` = '0'

On the ROUND linesales / orders * 100) AS buyoutThere's no sales and orders. Although they are in the form of alias above (AS) ordersAS sales) How do you get access to these columns so you can take a ready value and re-use SUM()?

[meriah]

Unfortunately, sql can't turn to the listed column on his alias. There are three options:

1. Reuse of SUM
2. CTE (WITH), but as far as I know mysql does not support CTE.
3. Implement the request, for example:

    select prep.*,
       ROUND(`prep.sales` / `prep.orders` * 100) AS `buyout`  FROM   
(SELECT `A`.*,
       SUM(o.quantity) AS `orders`,
       SUM((CASE
                WHEN o.date >= ADDDATE(CURRENT_DATE(), -30 +1) THEN o.quantity
                ELSE 0
            END)) AS `orders_period`,
       SUM(s.quantity) AS `sales`,
       SUM((CASE
                WHEN s.date >= ADDDATE(CURRENT_DATE(), -30 +1) THEN s.quantity
                ELSE 0
            END)) AS `sales_period`
       FROM `data_goods` AS A
LEFT JOIN `data_orders` AS o ON o.wb_code = A.wb_code AND o.user = A.user AND o.key = A.key
LEFT JOIN `data_sales` AS s ON s.wb_code = A.wb_code AND s.user = A.user AND s.key = A.key AND s.sale_id LIKE 'S%'
WHERE A.`user` = '0') prep