Question

我有两个表，一个存储当前的价格v_prod_prices和td_prod_prices，其中包含所有产品的所有价格更新，下面的函数用于获取当前最低价格之间的百分比差异价格和以前的最低价格。我几乎只有一点点逻辑，我无法弄明白。

当前输出

目前的功能正在返回-71.42这是不正确的，因为它使用的10.00的当前价格是正确的，而34.99的先前价格是不正确的。

预期/期望的输出

它应该使用-50的当前价格和此前的10.00之前的最低价格返回20.00。

获得之前的最低价格时，td_prod_prices会忽略这些记录：

id      prod_id price   store   added
-----------------------------------------------
734     426     10.00   1       2016-01-22 02:05:17
819     426     42.99   3       2016-01-24 23:47:51
1052    426     34.99   4       2016-01-27 00:54:50

v_prod_prices

视图v_prod_prices仅包含基于td_prod_prices表格的每个商品的当前最低价格。

prod_id price   store   added
-------------------------------------------
426     34.99   4       2016-01-27 00:54:50
426     42.99   3       2016-01-24 23:47:51
426     10.00   1       2016-01-22 02:05:17
426     29.19   2       2016-01-15 14:09:53

td_prod_prices

td_prod_prices包含所有产品价格更新。

id      prod_id price   store   added
-----------------------------------------------
500     426     29.19   2       2016-01-15 14:09:53
660     426     20.00   1       2016-01-15 21:07:38
734     426     10.00   1       2016-01-22 02:05:17
819     426     42.99   3       2016-01-24 23:47:51
1052    426     34.99   4       2016-01-27 00:54:50

SQL

CREATE FUNCTION FN_GET_PROD_PRICE_CHANGE_DIFF (`prodId` BIGINT)
RETURNS DECIMAL(5,2)
BEGIN
    DECLARE `priceDiff` DECIMAL(5,2) DEFAULT 0;
    DECLARE `currentPrice`, `previousPrice` DOUBLE(7,2) DEFAULT 0;
    DECLARE `currentStore`, `previousStore` INT DEFAULT 0;
    DECLARE `currentAdded`, `previousAdded` TIMESTAMP;

    /* Get current price */
    SELECT MIN(`price`)
    , `store`
    , `added`
    INTO `currentPrice`
    , `currentStore`
    , `currentAdded`
    FROM `v_prod_prices`
    WHERE `prod_id` = `prodId`
    LIMIT 0,1;

    /* Get previous price */
    SELECT MIN(`spr`.`spr_price`) AS `price`
    , `spr`.`spr_str_id` AS `store`
    , `spr`.`spr_added` AS `added`
    INTO `previousPrice`
    , `previousStore`
    , `previousAdded`
    FROM `td_prod` `prod`
    JOIN `td_prod_prices` `spr` ON `prod`.`prod_id` = `spr`.`spr_prod_id`
    WHERE NOT EXISTS (
        SELECT 1
        FROM `td_prod_prices` `spr2`
        WHERE `spr`.`spr_prod_id` = `spr2`.`spr_prod_id`
        AND `spr`.`spr_str_id` = `spr2`.`spr_str_id`
        AND `spr`.`spr_added` < `spr2`.`spr_added`
    )
    AND `prod`.`prod_status` = 1
    AND `prod`.`prod_id` = prodId;

    IF `currentPrice` <> 0 AND `previousPrice` <> 0 AND `currentPrice` <> `previousPrice` THEN
        SET `priceDiff` = ((`currentPrice` - `previousPrice`) / `previousPrice`) * 100;
    END IF;

    RETURN `priceDiff`;
END//

Answer 1

最终让它发挥作用，在此发布以供类似情况下的任何人参考。我将其更改为获取当前最低价格记录的id，并在计算产品的先前最低价格时排除任何大于或等于id的记录。

CREATE FUNCTION FN_GET_PROD_PRICE_CHANGE_DIFF (`prodId` BIGINT)
RETURNS DECIMAL(5,2)
BEGIN
    DECLARE `priceDiff` DECIMAL(5,2) DEFAULT 0;
    DECLARE `currentPriceId` BIGINT(11) DEFAULT 0;
    DECLARE `currentPrice`, `previousPrice` DOUBLE(7,2) DEFAULT 0;

    /* Get current price */
    SELECT `price_id`
    , `price`
    INTO `currentPriceId`
    , `currentPrice`
    FROM `v_prod_prices`
    WHERE `prod_id` = `prodId`
    ORDER BY `price` ASC
    LIMIT 0,1;

    /* Get previous price */
    SELECT `spr`.`spr_price` AS `price`
    INTO `previousPrice`
    FROM `td_prod` `prod`
    JOIN `td_prod_prices` `spr` ON `prod`.`prod_id` = `spr`.`spr_prod_id`
    WHERE NOT EXISTS (
        SELECT 1
        FROM `td_prod_prices` `spr2`
        WHERE `spr`.`spr_prod_id` = `spr2`.`spr_prod_id`
        AND `spr`.`spr_str_id` = `spr2`.`spr_str_id`
        AND `spr`.`spr_added` < `spr2`.`spr_added`
        AND `spr`.`spr_added` > `currentAdded`
        AND `spr2`.`spr_id` < `currentPriceId`
    )
    AND `prod`.`prod_status` = 1
    AND `prod`.`prod_id` = prodId
    AND `spr`.`spr_id` < `currentPriceId`
    ORDER BY price ASC
    LIMIT 0,1;

    IF `currentPrice` <> 0 AND `previousPrice` <> 0 AND `currentPrice` <> `previousPrice` THEN
        SET `priceDiff` = ((`currentPrice` - `previousPrice`) / `previousPrice`) * 100;
    END IF;

    RETURN `priceDiff`;
END//

MySQL：产品当前最低价格/先前最低价格百分比差异

1 个答案: