我使用 PDO Mysql，并请求为我的数据库中的产品选择最便宜的报价。它工作正常，唯一的问题是它很慢（对于 200 个报价（并且仍然只有 25 个返回））它需要将近一秒钟，这比我的目标要高得多。
我不是 SQL 专家，所以我在这件事上寻求您的帮助。这是请求，如果需要，我很乐意提供更多信息：
SELECT
mo.id AS id,
mo.stock AS stock,
mo.price AS price,
mo.promotional_price AS promotional_price,
mo.picture_1 AS picture_1,
mo.picture_2 AS picture_2,
mo.picture_3 AS picture_3,
mo.picture_4 AS picture_4,
mo.picture_5 AS picture_5,
mo.title AS title,
mo.description AS description,
mo.state AS state,
mo.is_new AS is_new,
mo.is_original AS is_original,
c.name AS name,
u.id AS user_id,
u.username AS username,
u.postal_code AS postal_code,
p.name AS country_name,
ra.cache_rating_avg AS cache_rating_avg,
ra.cache_rating_nb AS cache_rating_nb,
GROUP_CONCAT(md.delivery_mode_id SEPARATOR ', ') AS delivery_mode_ids,
GROUP_CONCAT(ri.title SEPARATOR ', ') AS delivery_mode_titles
FROM
mp_offer mo, catalog_product_i18n c,
ref_country_i18n p, mp_offer_delivery_mode md,
ref_delivery_mode r,
ref_delivery_mode_i18n ri, user u
LEFT JOIN mp_user_review_rating_i18n ra
ON u.id = ra.user_id
WHERE (mo.product_id = c.id
AND mo.culture = c.culture
AND mo.user_id = u.id
AND u.country_id = p.id
AND mo.id = md.offer_id
AND md.delivery_mode_id = ri.id
AND mo.culture = ri.culture)
AND (mo.culture = 1
AND p.culture = 1)
AND mo.is_deleted = 0
AND mo.product_id = 60
AND ((u.holiday_start IS NULL)
OR (u.holiday_start = '0000-00-00')
OR (u.holiday_end IS NULL)
OR (u.holiday_end = '0000-00-00')
OR (u.holiday_start > '2012-05-03')
OR (u.holiday_end < '2012-05-03'))
AND mo.stock > 0
GROUP BY mo.id
ORDER BY IF (mo.promotional_price IS NULL,
mo.price,
LEAST(mo.price, mo.promotional_price)) ASC
LIMIT 25 OFFSET 0;
我接受将“文化”设置为 1、未删除、有一些库存且卖家不在假期的特定产品的报价。我按价格订购（promotional_price 有一个）。
LEAST 是一个缓慢的函数吗？
这是 EXPLAIN 的输出：
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE c const PRIMARY,catalog_product_i18n_product,catalog_product_i18n_culture PRIMARY 8 const,const 1 "Using temporary; Using filesort"
1 SIMPLE mo ref PRIMARY,culture,is_deleted,product_id,user_id culture 4 const 3 "Using where with pushed condition"
1 SIMPLE u eq_ref PRIMARY,user_country PRIMARY 4 database.mo.user_id 1 "Using where with pushed condition"
1 SIMPLE p eq_ref PRIMARY,ref_country_i18n_culture PRIMARY 8 database.u.country_id,const 1
1 SIMPLE r ALL NULL NULL NULL NULL 3 "Using join buffer"
1 SIMPLE ra ALL NULL NULL NULL NULL 4
1 SIMPLE md ref PRIMARY,fk_offer_has_delivery_mode_delivery_mode1,fk_offer_has_delivery_mode_offer1 PRIMARY 4 database.mo.id 2
1 SIMPLE ri eq_ref PRIMARY PRIMARY 2 database.md.delivery_mode_id,const 1
提前感谢您在优化此请求方面的帮助。
Ĵ