Question

我试图查询我的产品表，以便我的查询返回某个价格范围内的产品集-产品具有许多变体，并且变体属于产品。我有以下正在运行的查询，但是它非常慢-查询需要1.66秒。

SELECT colortags.tag, products.*, (SELECT variants.price FROM variants WHERE variants.product_id = products.product_id LIMIT 1) price, collects.position 
FROM products
INNER JOIN wp_wps_collects collects 
ON products.product_id = collects.product_id 
AND collects.collection_id = 123456788
INNER JOIN wp_wps_tags colortags 
ON colortags.product_id = collects.product_id 
AND (colortags.tag = 'black' OR colortags.tag = 'nav') 
INNER JOIN wp_wps_tags styletags 
ON styletags.product_id = collects.product_id 
AND (styletags.tag = 'purses')
WHERE (SELECT variants.price FROM variants WHERE variants.product_id = products.product_id AND variants.price >= 200 AND variants.price < 300 LIMIT 1) > 0
AND (SELECT variants.price FROM variants WHERE variants.product_id = products.product_id AND variants.price >= 200 AND variants.price < 300 LIMIT 1) <> 0

在WHERE语句中，我尝试仅在SELECT语句中检查由子查询创建的price值，但是MYSQL告诉我price未定义。这是SQL：

SELECT colortags.tag, products.*, (SELECT variants.price FROM wp_wps_variants variants WHERE variants.product_id = products.product_id LIMIT 1) price, collects.position 
FROM wp_wps_products products
INNER JOIN wp_wps_collects collects 
ON products.product_id = collects.product_id 
AND collects.collection_id = 98515058801
INNER JOIN wp_wps_tags colortags 
ON colortags.product_id = collects.product_id 
AND (colortags.tag = 'color:generic-black' OR colortags.tag = 'color:navy') 
INNER JOIN wp_wps_tags styletags 
ON styletags.product_id = collects.product_id 
AND (styletags.tag = 'style:totes')
WHERE price >= 200 
AND price < 300

这是我从上面的SQL中收到的错误消息：

“ where子句”中的未知列“ price”

我还尝试在variants表上使用一系列联接，但是随后我得到了重复的产品。这是SQL

SELECT colortags.tag, products.*, (SELECT variants.price FROM variants WHERE variants.product_id = products.product_id LIMIT 1) price, collects.position 
FROM products
INNER JOIN collects 
ON products.product_id = collects.product_id 
AND collects.collection_id = 1234566
INNER JOIN colortags 
ON colortags.product_id = collects.product_id 
AND (colortags.tag = 'black' OR colortags.tag = 'navy') 
INNER JOIN styletags 
ON styletags.product_id = collects.product_id 
AND (styletags.tag = 'purses')
INNER JOIN variants
ON variants.product_id = products.product_id
AND variants.price >= 200 
AND variants.price < 300
AND variants.price > 0
AND variants.price <> 0

我想要的是从第一个SQL语句获得的查询结果，而不会影响性能。我想认为我可以在变量表上用INNER JOIN编写SQL，以过滤出不正确价格的变量，而又不会得到重复的产品，但是我无法确定该怎么做。

有人知道我如何在这里编写SQL，使我能够查询一定价格范围内的产品，而又不会退回重复的产品，而不会严重影响性能？

Answer 1

如果将查询封装在另一个查询中，则可以在price子句中使用where

SELECT * from (
    SELECT colortags.tag, products.*, (SELECT variants.price FROM variants WHERE variants.product_id = products.product_id LIMIT 1) price, collects.position 
    FROM products
    INNER JOIN wp_wps_collects collects 
    ON products.product_id = collects.product_id 
    AND collects.collection_id = 123456788
    INNER JOIN wp_wps_tags colortags 
    ON colortags.product_id = collects.product_id 
    AND (colortags.tag = 'black' OR colortags.tag = 'nav') 
    INNER JOIN wp_wps_tags styletags 
    ON styletags.product_id = collects.product_id 
    AND (styletags.tag = 'purses')
    WHERE (SELECT variants.price FROM variants WHERE variants.product_id = products.product_id AND variants.price >= 200 AND variants.price < 300 LIMIT 1) > 0
) t 
WHERE t.price >= 200 and t.price < 300

Answer 2

您正在执行半联接，这意味着您想进行联接，但是即使有多个匹配项，也只需要一行结果。

执行此操作的一种方法是联接到派生表，该表在子查询中使用GROUP BY将每个product_id的变体减少为一行。

SELECT colortags.tag, products.*, prices.price, collects.position 
FROM products
INNER JOIN wp_wps_collects collects 
  ON products.product_id = collects.product_id 
  AND collects.collection_id = 123456788
INNER JOIN wp_wps_tags colortags 
  ON colortags.product_id = collects.product_id 
  AND (colortags.tag = 'black' OR colortags.tag = 'nav') 
INNER JOIN wp_wps_tags styletags 
  ON styletags.product_id = collects.product_id 
  AND (styletags.tag = 'purses')
INNER JOIN (
  SELECT v.product_id, MIN(v.price) AS price FROM variants v
  INNER JOIN wp_wps_collects c ON v.product_id = c.product_id
  WHERE c.collection_id = 123456788
  GROUP BY product_id ORDER BY NULL
) prices
  ON products.product_id = prices.product_id

我假设您会对每种产品的最低价格感兴趣。您也可以在派生表中使用MAX()。

我必须将联接复制到wp_wps_collects，因此派生表将限于与您要查询的集合相关的产品。否则，如果您有数百万种产品，则派生表将变得很大，以至于将产生另一个性能问题。

对可变价格范围内的产品进行MYSQL查询，没有重复项

2 个答案: